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linux/drivers/gpu/drm/display/drm_dp_helper.c
Val Packett 4aa8961b1b drm/dp: drm_edp_backlight_set_level: do not always send 3-byte commands 
At least some panels using the LSB register are not happy with the
unconditional increase of the command buffer to 3 bytes.

With the BOE NE14QDM in my Dell Latitude 7455, the recent patches for
luminance based brightness have introduced a regression: the brightness
range stopped being contiguous and became nonsensical (it probably was
interpreting the last 2 bytes of the buffer and not the first 2).

Change from using a fixed sizeof() to a length variable that's only
set to 3 when luminance is used. Let's leave the default as 2 even for
the single-byte version, since that's how it worked before.

Fixes: f2db78e37f ("drm/dp: Modify drm_edp_backlight_set_level")
Signed-off-by: Val Packett <val@packett.cool>
Tested-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://lore.kernel.org/r/20250706204446.8918-1-val@packett.cool
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
2025-08-21 13:41:59 +03:00

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/*
* Copyright © 2009 Keith Packard
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting documentation, and
* that the name of the copyright holders not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. The copyright holders make no representations
* about the suitability of this software for any purpose. It is provided "as
* is" without express or implied warranty.
*
* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*/
#include <linux/backlight.h>
#include <linux/delay.h>
#include <linux/dynamic_debug.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/string_helpers.h>
#include <drm/display/drm_dp_helper.h>
#include <drm/display/drm_dp_mst_helper.h>
#include <drm/drm_edid.h>
#include <drm/drm_fixed.h>
#include <drm/drm_print.h>
#include <drm/drm_vblank.h>
#include <drm/drm_panel.h>
#include "drm_dp_helper_internal.h"
DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
"DRM_UT_CORE",
"DRM_UT_DRIVER",
"DRM_UT_KMS",
"DRM_UT_PRIME",
"DRM_UT_ATOMIC",
"DRM_UT_VBL",
"DRM_UT_STATE",
"DRM_UT_LEASE",
"DRM_UT_DP",
"DRM_UT_DRMRES");
struct dp_aux_backlight {
struct backlight_device *base;
struct drm_dp_aux *aux;
struct drm_edp_backlight_info info;
bool enabled;
};
/**
* DOC: dp helpers
*
* These functions contain some common logic and helpers at various abstraction
* levels to deal with Display Port sink devices and related things like DP aux
* channel transfers, EDID reading over DP aux channels, decoding certain DPCD
* blocks, ...
*/
/* Helpers for DP link training */
static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)
{
return link_status[r - DP_LANE0_1_STATUS];
}
static u8 dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane)
{
int i = DP_LANE0_1_STATUS + (lane >> 1);
int s = (lane & 1) * 4;
u8 l = dp_link_status(link_status, i);
return (l >> s) & 0xf;
}
bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane_count)
{
u8 lane_align;
u8 lane_status;
int lane;
lane_align = dp_link_status(link_status,
DP_LANE_ALIGN_STATUS_UPDATED);
if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0)
return false;
for (lane = 0; lane < lane_count; lane++) {
lane_status = dp_get_lane_status(link_status, lane);
if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS)
return false;
}
return true;
}
EXPORT_SYMBOL(drm_dp_channel_eq_ok);
bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane_count)
{
int lane;
u8 lane_status;
for (lane = 0; lane < lane_count; lane++) {
lane_status = dp_get_lane_status(link_status, lane);
if ((lane_status & DP_LANE_CR_DONE) == 0)
return false;
}
return true;
}
EXPORT_SYMBOL(drm_dp_clock_recovery_ok);
u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane)
{
int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
int s = ((lane & 1) ?
DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT :
DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT);
u8 l = dp_link_status(link_status, i);
return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT;
}
EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage);
u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane)
{
int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
int s = ((lane & 1) ?
DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT :
DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT);
u8 l = dp_link_status(link_status, i);
return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT;
}
EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis);
/* DP 2.0 128b/132b */
u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane)
{
int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
int s = ((lane & 1) ?
DP_ADJUST_TX_FFE_PRESET_LANE1_SHIFT :
DP_ADJUST_TX_FFE_PRESET_LANE0_SHIFT);
u8 l = dp_link_status(link_status, i);
return (l >> s) & 0xf;
}
EXPORT_SYMBOL(drm_dp_get_adjust_tx_ffe_preset);
/* DP 2.0 errata for 128b/132b */
bool drm_dp_128b132b_lane_channel_eq_done(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane_count)
{
u8 lane_align, lane_status;
int lane;
lane_align = dp_link_status(link_status, DP_LANE_ALIGN_STATUS_UPDATED);
if (!(lane_align & DP_INTERLANE_ALIGN_DONE))
return false;
for (lane = 0; lane < lane_count; lane++) {
lane_status = dp_get_lane_status(link_status, lane);
if (!(lane_status & DP_LANE_CHANNEL_EQ_DONE))
return false;
}
return true;
}
EXPORT_SYMBOL(drm_dp_128b132b_lane_channel_eq_done);
/* DP 2.0 errata for 128b/132b */
bool drm_dp_128b132b_lane_symbol_locked(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane_count)
{
u8 lane_status;
int lane;
for (lane = 0; lane < lane_count; lane++) {
lane_status = dp_get_lane_status(link_status, lane);
if (!(lane_status & DP_LANE_SYMBOL_LOCKED))
return false;
}
return true;
}
EXPORT_SYMBOL(drm_dp_128b132b_lane_symbol_locked);
/* DP 2.0 errata for 128b/132b */
bool drm_dp_128b132b_eq_interlane_align_done(const u8 link_status[DP_LINK_STATUS_SIZE])
{
u8 status = dp_link_status(link_status, DP_LANE_ALIGN_STATUS_UPDATED);
return status & DP_128B132B_DPRX_EQ_INTERLANE_ALIGN_DONE;
}
EXPORT_SYMBOL(drm_dp_128b132b_eq_interlane_align_done);
/* DP 2.0 errata for 128b/132b */
bool drm_dp_128b132b_cds_interlane_align_done(const u8 link_status[DP_LINK_STATUS_SIZE])
{
u8 status = dp_link_status(link_status, DP_LANE_ALIGN_STATUS_UPDATED);
return status & DP_128B132B_DPRX_CDS_INTERLANE_ALIGN_DONE;
}
EXPORT_SYMBOL(drm_dp_128b132b_cds_interlane_align_done);
/* DP 2.0 errata for 128b/132b */
bool drm_dp_128b132b_link_training_failed(const u8 link_status[DP_LINK_STATUS_SIZE])
{
u8 status = dp_link_status(link_status, DP_LANE_ALIGN_STATUS_UPDATED);
return status & DP_128B132B_LT_FAILED;
}
EXPORT_SYMBOL(drm_dp_128b132b_link_training_failed);
static int __8b10b_clock_recovery_delay_us(const struct drm_dp_aux *aux, u8 rd_interval)
{
if (rd_interval > 4)
drm_dbg_kms(aux->drm_dev, "%s: invalid AUX interval 0x%02x (max 4)\n",
aux->name, rd_interval);
if (rd_interval == 0)
return 100;
return rd_interval * 4 * USEC_PER_MSEC;
}
static int __8b10b_channel_eq_delay_us(const struct drm_dp_aux *aux, u8 rd_interval)
{
if (rd_interval > 4)
drm_dbg_kms(aux->drm_dev, "%s: invalid AUX interval 0x%02x (max 4)\n",
aux->name, rd_interval);
if (rd_interval == 0)
return 400;
return rd_interval * 4 * USEC_PER_MSEC;
}
static int __128b132b_channel_eq_delay_us(const struct drm_dp_aux *aux, u8 rd_interval)
{
switch (rd_interval) {
default:
drm_dbg_kms(aux->drm_dev, "%s: invalid AUX interval 0x%02x\n",
aux->name, rd_interval);
fallthrough;
case DP_128B132B_TRAINING_AUX_RD_INTERVAL_400_US:
return 400;
case DP_128B132B_TRAINING_AUX_RD_INTERVAL_4_MS:
return 4000;
case DP_128B132B_TRAINING_AUX_RD_INTERVAL_8_MS:
return 8000;
case DP_128B132B_TRAINING_AUX_RD_INTERVAL_12_MS:
return 12000;
case DP_128B132B_TRAINING_AUX_RD_INTERVAL_16_MS:
return 16000;
case DP_128B132B_TRAINING_AUX_RD_INTERVAL_32_MS:
return 32000;
case DP_128B132B_TRAINING_AUX_RD_INTERVAL_64_MS:
return 64000;
}
}
/*
* The link training delays are different for:
*
* - Clock recovery vs. channel equalization
* - DPRX vs. LTTPR
* - 128b/132b vs. 8b/10b
* - DPCD rev 1.3 vs. later
*
* Get the correct delay in us, reading DPCD if necessary.
*/
static int __read_delay(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE],
enum drm_dp_phy dp_phy, bool uhbr, bool cr)
{
int (*parse)(const struct drm_dp_aux *aux, u8 rd_interval);
unsigned int offset;
u8 rd_interval, mask;
if (dp_phy == DP_PHY_DPRX) {
if (uhbr) {
if (cr)
return 100;
offset = DP_128B132B_TRAINING_AUX_RD_INTERVAL;
mask = DP_128B132B_TRAINING_AUX_RD_INTERVAL_MASK;
parse = __128b132b_channel_eq_delay_us;
} else {
if (cr && dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14)
return 100;
offset = DP_TRAINING_AUX_RD_INTERVAL;
mask = DP_TRAINING_AUX_RD_MASK;
if (cr)
parse = __8b10b_clock_recovery_delay_us;
else
parse = __8b10b_channel_eq_delay_us;
}
} else {
if (uhbr) {
offset = DP_128B132B_TRAINING_AUX_RD_INTERVAL_PHY_REPEATER(dp_phy);
mask = DP_128B132B_TRAINING_AUX_RD_INTERVAL_MASK;
parse = __128b132b_channel_eq_delay_us;
} else {
if (cr)
return 100;
offset = DP_TRAINING_AUX_RD_INTERVAL_PHY_REPEATER(dp_phy);
mask = DP_TRAINING_AUX_RD_MASK;
parse = __8b10b_channel_eq_delay_us;
}
}
if (offset < DP_RECEIVER_CAP_SIZE) {
rd_interval = dpcd[offset];
} else {
if (drm_dp_dpcd_read_byte(aux, offset, &rd_interval) < 0) {
drm_dbg_kms(aux->drm_dev, "%s: failed rd interval read\n",
aux->name);
/* arbitrary default delay */
return 400;
}
}
return parse(aux, rd_interval & mask);
}
int drm_dp_read_clock_recovery_delay(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE],
enum drm_dp_phy dp_phy, bool uhbr)
{
return __read_delay(aux, dpcd, dp_phy, uhbr, true);
}
EXPORT_SYMBOL(drm_dp_read_clock_recovery_delay);
int drm_dp_read_channel_eq_delay(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE],
enum drm_dp_phy dp_phy, bool uhbr)
{
return __read_delay(aux, dpcd, dp_phy, uhbr, false);
}
EXPORT_SYMBOL(drm_dp_read_channel_eq_delay);
/* Per DP 2.0 Errata */
int drm_dp_128b132b_read_aux_rd_interval(struct drm_dp_aux *aux)
{
int unit;
u8 val;
if (drm_dp_dpcd_read_byte(aux, DP_128B132B_TRAINING_AUX_RD_INTERVAL, &val) < 0) {
drm_err(aux->drm_dev, "%s: failed rd interval read\n",
aux->name);
/* default to max */
val = DP_128B132B_TRAINING_AUX_RD_INTERVAL_MASK;
}
unit = (val & DP_128B132B_TRAINING_AUX_RD_INTERVAL_1MS_UNIT) ? 1 : 2;
val &= DP_128B132B_TRAINING_AUX_RD_INTERVAL_MASK;
return (val + 1) * unit * 1000;
}
EXPORT_SYMBOL(drm_dp_128b132b_read_aux_rd_interval);
void drm_dp_link_train_clock_recovery_delay(const struct drm_dp_aux *aux,
const u8 dpcd[DP_RECEIVER_CAP_SIZE])
{
u8 rd_interval = dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
DP_TRAINING_AUX_RD_MASK;
int delay_us;
if (dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14)
delay_us = 100;
else
delay_us = __8b10b_clock_recovery_delay_us(aux, rd_interval);
usleep_range(delay_us, delay_us * 2);
}
EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay);
static void __drm_dp_link_train_channel_eq_delay(const struct drm_dp_aux *aux,
u8 rd_interval)
{
int delay_us = __8b10b_channel_eq_delay_us(aux, rd_interval);
usleep_range(delay_us, delay_us * 2);
}
void drm_dp_link_train_channel_eq_delay(const struct drm_dp_aux *aux,
const u8 dpcd[DP_RECEIVER_CAP_SIZE])
{
__drm_dp_link_train_channel_eq_delay(aux,
dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
DP_TRAINING_AUX_RD_MASK);
}
EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay);
/**
* drm_dp_phy_name() - Get the name of the given DP PHY
* @dp_phy: The DP PHY identifier
*
* Given the @dp_phy, get a user friendly name of the DP PHY, either "DPRX" or
* "LTTPR <N>", or "<INVALID DP PHY>" on errors. The returned string is always
* non-NULL and valid.
*
* Returns: Name of the DP PHY.
*/
const char *drm_dp_phy_name(enum drm_dp_phy dp_phy)
{
static const char * const phy_names[] = {
[DP_PHY_DPRX] = "DPRX",
[DP_PHY_LTTPR1] = "LTTPR 1",
[DP_PHY_LTTPR2] = "LTTPR 2",
[DP_PHY_LTTPR3] = "LTTPR 3",
[DP_PHY_LTTPR4] = "LTTPR 4",
[DP_PHY_LTTPR5] = "LTTPR 5",
[DP_PHY_LTTPR6] = "LTTPR 6",
[DP_PHY_LTTPR7] = "LTTPR 7",
[DP_PHY_LTTPR8] = "LTTPR 8",
};
if (dp_phy < 0 || dp_phy >= ARRAY_SIZE(phy_names) ||
WARN_ON(!phy_names[dp_phy]))
return "<INVALID DP PHY>";
return phy_names[dp_phy];
}
EXPORT_SYMBOL(drm_dp_phy_name);
void drm_dp_lttpr_link_train_clock_recovery_delay(void)
{
usleep_range(100, 200);
}
EXPORT_SYMBOL(drm_dp_lttpr_link_train_clock_recovery_delay);
static u8 dp_lttpr_phy_cap(const u8 phy_cap[DP_LTTPR_PHY_CAP_SIZE], int r)
{
return phy_cap[r - DP_TRAINING_AUX_RD_INTERVAL_PHY_REPEATER1];
}
void drm_dp_lttpr_link_train_channel_eq_delay(const struct drm_dp_aux *aux,
const u8 phy_cap[DP_LTTPR_PHY_CAP_SIZE])
{
u8 interval = dp_lttpr_phy_cap(phy_cap,
DP_TRAINING_AUX_RD_INTERVAL_PHY_REPEATER1) &
DP_TRAINING_AUX_RD_MASK;
__drm_dp_link_train_channel_eq_delay(aux, interval);
}
EXPORT_SYMBOL(drm_dp_lttpr_link_train_channel_eq_delay);
/**
* drm_dp_lttpr_wake_timeout_setup() - Grant extended time for sink to wake up
* @aux: The DP AUX channel to use
* @transparent_mode: This is true if lttpr is in transparent mode
*
* This function checks if the sink needs any extended wake time, if it does
* it grants this request. Post this setup the source device can keep trying
* the Aux transaction till the granted wake timeout.
* If this function is not called all Aux transactions are expected to take
* a default of 1ms before they throw an error.
*/
void drm_dp_lttpr_wake_timeout_setup(struct drm_dp_aux *aux, bool transparent_mode)
{
u8 val = 1;
int ret;
if (transparent_mode) {
static const u8 timeout_mapping[] = {
[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_1_MS] = 1,
[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_20_MS] = 20,
[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_40_MS] = 40,
[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_60_MS] = 60,
[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_80_MS] = 80,
[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_100_MS] = 100,
};
ret = drm_dp_dpcd_readb(aux, DP_EXTENDED_DPRX_SLEEP_WAKE_TIMEOUT_REQUEST, &val);
if (ret != 1) {
drm_dbg_kms(aux->drm_dev,
"Failed to read Extended sleep wake timeout request\n");
return;
}
val = (val < sizeof(timeout_mapping) && timeout_mapping[val]) ?
timeout_mapping[val] : 1;
if (val > 1)
drm_dp_dpcd_writeb(aux,
DP_EXTENDED_DPRX_SLEEP_WAKE_TIMEOUT_GRANT,
DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_GRANTED);
} else {
ret = drm_dp_dpcd_readb(aux, DP_PHY_REPEATER_EXTENDED_WAIT_TIMEOUT, &val);
if (ret != 1) {
drm_dbg_kms(aux->drm_dev,
"Failed to read Extended sleep wake timeout request\n");
return;
}
val = (val & DP_EXTENDED_WAKE_TIMEOUT_REQUEST_MASK) ?
(val & DP_EXTENDED_WAKE_TIMEOUT_REQUEST_MASK) * 10 : 1;
if (val > 1)
drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_EXTENDED_WAIT_TIMEOUT,
DP_EXTENDED_WAKE_TIMEOUT_GRANT);
}
}
EXPORT_SYMBOL(drm_dp_lttpr_wake_timeout_setup);
u8 drm_dp_link_rate_to_bw_code(int link_rate)
{
switch (link_rate) {
case 1000000:
return DP_LINK_BW_10;
case 1350000:
return DP_LINK_BW_13_5;
case 2000000:
return DP_LINK_BW_20;
default:
/* Spec says link_bw = link_rate / 0.27Gbps */
return link_rate / 27000;
}
}
EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code);
int drm_dp_bw_code_to_link_rate(u8 link_bw)
{
switch (link_bw) {
case DP_LINK_BW_10:
return 1000000;
case DP_LINK_BW_13_5:
return 1350000;
case DP_LINK_BW_20:
return 2000000;
default:
/* Spec says link_rate = link_bw * 0.27Gbps */
return link_bw * 27000;
}
}
EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
#define AUX_RETRY_INTERVAL 500 /* us */
static inline void
drm_dp_dump_access(const struct drm_dp_aux *aux,
u8 request, uint offset, void *buffer, int ret)
{
const char *arrow = request == DP_AUX_NATIVE_READ ? "->" : "<-";
if (ret > 0)
drm_dbg_dp(aux->drm_dev, "%s: 0x%05x AUX %s (ret=%3d) %*ph\n",
aux->name, offset, arrow, ret, min(ret, 20), buffer);
else
drm_dbg_dp(aux->drm_dev, "%s: 0x%05x AUX %s (ret=%3d)\n",
aux->name, offset, arrow, ret);
}
/**
* DOC: dp helpers
*
* The DisplayPort AUX channel is an abstraction to allow generic, driver-
* independent access to AUX functionality. Drivers can take advantage of
* this by filling in the fields of the drm_dp_aux structure.
*
* Transactions are described using a hardware-independent drm_dp_aux_msg
* structure, which is passed into a driver's .transfer() implementation.
* Both native and I2C-over-AUX transactions are supported.
*/
static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
unsigned int offset, void *buffer, size_t size)
{
struct drm_dp_aux_msg msg;
unsigned int retry, native_reply;
int err = 0, ret = 0;
memset(&msg, 0, sizeof(msg));
msg.address = offset;
msg.request = request;
msg.buffer = buffer;
msg.size = size;
mutex_lock(&aux->hw_mutex);
/*
* If the device attached to the aux bus is powered down then there's
* no reason to attempt a transfer. Error out immediately.
*/
if (aux->powered_down) {
ret = -EBUSY;
goto unlock;
}
/*
* The specification doesn't give any recommendation on how often to
* retry native transactions. We used to retry 7 times like for
* aux i2c transactions but real world devices this wasn't
* sufficient, bump to 32 which makes Dell 4k monitors happier.
*/
for (retry = 0; retry < 32; retry++) {
if (ret != 0 && ret != -ETIMEDOUT) {
usleep_range(AUX_RETRY_INTERVAL,
AUX_RETRY_INTERVAL + 100);
}
ret = aux->transfer(aux, &msg);
if (ret >= 0) {
native_reply = msg.reply & DP_AUX_NATIVE_REPLY_MASK;
if (native_reply == DP_AUX_NATIVE_REPLY_ACK) {
if (ret == size)
goto unlock;
ret = -EPROTO;
} else
ret = -EIO;
}
/*
* We want the error we return to be the error we received on
* the first transaction, since we may get a different error the
* next time we retry
*/
if (!err)
err = ret;
}
drm_dbg_kms(aux->drm_dev, "%s: Too many retries, giving up. First error: %d\n",
aux->name, err);
ret = err;
unlock:
mutex_unlock(&aux->hw_mutex);
return ret;
}
/**
* drm_dp_dpcd_probe() - probe a given DPCD address with a 1-byte read access
* @aux: DisplayPort AUX channel (SST)
* @offset: address of the register to probe
*
* Probe the provided DPCD address by reading 1 byte from it. The function can
* be used to trigger some side-effect the read access has, like waking up the
* sink, without the need for the read-out value.
*
* Returns 0 if the read access suceeded, or a negative error code on failure.
*/
int drm_dp_dpcd_probe(struct drm_dp_aux *aux, unsigned int offset)
{
u8 buffer;
int ret;
ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, &buffer, 1);
WARN_ON(ret == 0);
drm_dp_dump_access(aux, DP_AUX_NATIVE_READ, offset, &buffer, ret);
return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL(drm_dp_dpcd_probe);
/**
* drm_dp_dpcd_set_powered() - Set whether the DP device is powered
* @aux: DisplayPort AUX channel; for convenience it's OK to pass NULL here
* and the function will be a no-op.
* @powered: true if powered; false if not
*
* If the endpoint device on the DP AUX bus is known to be powered down
* then this function can be called to make future transfers fail immediately
* instead of needing to time out.
*
* If this function is never called then a device defaults to being powered.
*/
void drm_dp_dpcd_set_powered(struct drm_dp_aux *aux, bool powered)
{
if (!aux)
return;
mutex_lock(&aux->hw_mutex);
aux->powered_down = !powered;
mutex_unlock(&aux->hw_mutex);
}
EXPORT_SYMBOL(drm_dp_dpcd_set_powered);
/**
* drm_dp_dpcd_set_probe() - Set whether a probing before DPCD access is done
* @aux: DisplayPort AUX channel
* @enable: Enable the probing if required
*/
void drm_dp_dpcd_set_probe(struct drm_dp_aux *aux, bool enable)
{
WRITE_ONCE(aux->dpcd_probe_disabled, !enable);
}
EXPORT_SYMBOL(drm_dp_dpcd_set_probe);
static bool dpcd_access_needs_probe(struct drm_dp_aux *aux)
{
/*
* HP ZR24w corrupts the first DPCD access after entering power save
* mode. Eg. on a read, the entire buffer will be filled with the same
* byte. Do a throw away read to avoid corrupting anything we care
* about. Afterwards things will work correctly until the monitor
* gets woken up and subsequently re-enters power save mode.
*
* The user pressing any button on the monitor is enough to wake it
* up, so there is no particularly good place to do the workaround.
* We just have to do it before any DPCD access and hope that the
* monitor doesn't power down exactly after the throw away read.
*/
return !aux->is_remote && !READ_ONCE(aux->dpcd_probe_disabled);
}
/**
* drm_dp_dpcd_read() - read a series of bytes from the DPCD
* @aux: DisplayPort AUX channel (SST or MST)
* @offset: address of the (first) register to read
* @buffer: buffer to store the register values
* @size: number of bytes in @buffer
*
* Returns the number of bytes transferred on success, or a negative error
* code on failure. -EIO is returned if the request was NAKed by the sink or
* if the retry count was exceeded. If not all bytes were transferred, this
* function returns -EPROTO. Errors from the underlying AUX channel transfer
* function, with the exception of -EBUSY (which causes the transaction to
* be retried), are propagated to the caller.
*
* In most of the cases you want to use drm_dp_dpcd_read_data() instead.
*/
ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
void *buffer, size_t size)
{
int ret;
if (dpcd_access_needs_probe(aux)) {
ret = drm_dp_dpcd_probe(aux, DP_TRAINING_PATTERN_SET);
if (ret < 0)
return ret;
}
if (aux->is_remote)
ret = drm_dp_mst_dpcd_read(aux, offset, buffer, size);
else
ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset,
buffer, size);
drm_dp_dump_access(aux, DP_AUX_NATIVE_READ, offset, buffer, ret);
return ret;
}
EXPORT_SYMBOL(drm_dp_dpcd_read);
/**
* drm_dp_dpcd_write() - write a series of bytes to the DPCD
* @aux: DisplayPort AUX channel (SST or MST)
* @offset: address of the (first) register to write
* @buffer: buffer containing the values to write
* @size: number of bytes in @buffer
*
* Returns the number of bytes transferred on success, or a negative error
* code on failure. -EIO is returned if the request was NAKed by the sink or
* if the retry count was exceeded. If not all bytes were transferred, this
* function returns -EPROTO. Errors from the underlying AUX channel transfer
* function, with the exception of -EBUSY (which causes the transaction to
* be retried), are propagated to the caller.
*
* In most of the cases you want to use drm_dp_dpcd_write_data() instead.
*/
ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
void *buffer, size_t size)
{
int ret;
if (aux->is_remote)
ret = drm_dp_mst_dpcd_write(aux, offset, buffer, size);
else
ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset,
buffer, size);
drm_dp_dump_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer, ret);
return ret;
}
EXPORT_SYMBOL(drm_dp_dpcd_write);
/**
* drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)
* @aux: DisplayPort AUX channel
* @status: buffer to store the link status in (must be at least 6 bytes)
*
* Returns a negative error code on failure or 0 on success.
*/
int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
u8 status[DP_LINK_STATUS_SIZE])
{
return drm_dp_dpcd_read_data(aux, DP_LANE0_1_STATUS, status,
DP_LINK_STATUS_SIZE);
}
EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);
/**
* drm_dp_dpcd_read_phy_link_status - get the link status information for a DP PHY
* @aux: DisplayPort AUX channel
* @dp_phy: the DP PHY to get the link status for
* @link_status: buffer to return the status in
*
* Fetch the AUX DPCD registers for the DPRX or an LTTPR PHY link status. The
* layout of the returned @link_status matches the DPCD register layout of the
* DPRX PHY link status.
*
* Returns 0 if the information was read successfully or a negative error code
* on failure.
*/
int drm_dp_dpcd_read_phy_link_status(struct drm_dp_aux *aux,
enum drm_dp_phy dp_phy,
u8 link_status[DP_LINK_STATUS_SIZE])
{
int ret;
if (dp_phy == DP_PHY_DPRX)
return drm_dp_dpcd_read_data(aux,
DP_LANE0_1_STATUS,
link_status,
DP_LINK_STATUS_SIZE);
ret = drm_dp_dpcd_read_data(aux,
DP_LANE0_1_STATUS_PHY_REPEATER(dp_phy),
link_status,
DP_LINK_STATUS_SIZE - 1);
if (ret < 0)
return ret;
/* Convert the LTTPR to the sink PHY link status layout */
memmove(&link_status[DP_SINK_STATUS - DP_LANE0_1_STATUS + 1],
&link_status[DP_SINK_STATUS - DP_LANE0_1_STATUS],
DP_LINK_STATUS_SIZE - (DP_SINK_STATUS - DP_LANE0_1_STATUS) - 1);
link_status[DP_SINK_STATUS - DP_LANE0_1_STATUS] = 0;
return 0;
}
EXPORT_SYMBOL(drm_dp_dpcd_read_phy_link_status);
/**
* drm_dp_link_power_up() - power up a DisplayPort link
* @aux: DisplayPort AUX channel
* @revision: DPCD revision supported on the link
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_link_power_up(struct drm_dp_aux *aux, unsigned char revision)
{
u8 value;
int err;
/* DP_SET_POWER register is only available on DPCD v1.1 and later */
if (revision < DP_DPCD_REV_11)
return 0;
err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
if (err < 0)
return err;
value &= ~DP_SET_POWER_MASK;
value |= DP_SET_POWER_D0;
err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
if (err < 0)
return err;
/*
* According to the DP 1.1 specification, a "Sink Device must exit the
* power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
* Control Field" (register 0x600).
*/
usleep_range(1000, 2000);
return 0;
}
EXPORT_SYMBOL(drm_dp_link_power_up);
/**
* drm_dp_link_power_down() - power down a DisplayPort link
* @aux: DisplayPort AUX channel
* @revision: DPCD revision supported on the link
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_link_power_down(struct drm_dp_aux *aux, unsigned char revision)
{
u8 value;
int err;
/* DP_SET_POWER register is only available on DPCD v1.1 and later */
if (revision < DP_DPCD_REV_11)
return 0;
err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
if (err < 0)
return err;
value &= ~DP_SET_POWER_MASK;
value |= DP_SET_POWER_D3;
err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
if (err < 0)
return err;
return 0;
}
EXPORT_SYMBOL(drm_dp_link_power_down);
static int read_payload_update_status(struct drm_dp_aux *aux)
{
int ret;
u8 status;
ret = drm_dp_dpcd_read_byte(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
if (ret < 0)
return ret;
return status;
}
/**
* drm_dp_dpcd_write_payload() - Write Virtual Channel information to payload table
* @aux: DisplayPort AUX channel
* @vcpid: Virtual Channel Payload ID
* @start_time_slot: Starting time slot
* @time_slot_count: Time slot count
*
* Write the Virtual Channel payload allocation table, checking the payload
* update status and retrying as necessary.
*
* Returns:
* 0 on success, negative error otherwise
*/
int drm_dp_dpcd_write_payload(struct drm_dp_aux *aux,
int vcpid, u8 start_time_slot, u8 time_slot_count)
{
u8 payload_alloc[3], status;
int ret;
int retries = 0;
drm_dp_dpcd_write_byte(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS,
DP_PAYLOAD_TABLE_UPDATED);
payload_alloc[0] = vcpid;
payload_alloc[1] = start_time_slot;
payload_alloc[2] = time_slot_count;
ret = drm_dp_dpcd_write_data(aux, DP_PAYLOAD_ALLOCATE_SET, payload_alloc, 3);
if (ret < 0) {
drm_dbg_kms(aux->drm_dev, "failed to write payload allocation %d\n", ret);
goto fail;
}
retry:
ret = drm_dp_dpcd_read_byte(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
if (ret < 0) {
drm_dbg_kms(aux->drm_dev, "failed to read payload table status %d\n", ret);
goto fail;
}
if (!(status & DP_PAYLOAD_TABLE_UPDATED)) {
retries++;
if (retries < 20) {
usleep_range(10000, 20000);
goto retry;
}
drm_dbg_kms(aux->drm_dev, "status not set after read payload table status %d\n",
status);
ret = -EINVAL;
goto fail;
}
ret = 0;
fail:
return ret;
}
EXPORT_SYMBOL(drm_dp_dpcd_write_payload);
/**
* drm_dp_dpcd_clear_payload() - Clear the entire VC Payload ID table
* @aux: DisplayPort AUX channel
*
* Clear the entire VC Payload ID table.
*
* Returns: 0 on success, negative error code on errors.
*/
int drm_dp_dpcd_clear_payload(struct drm_dp_aux *aux)
{
return drm_dp_dpcd_write_payload(aux, 0, 0, 0x3f);
}
EXPORT_SYMBOL(drm_dp_dpcd_clear_payload);
/**
* drm_dp_dpcd_poll_act_handled() - Poll for ACT handled status
* @aux: DisplayPort AUX channel
* @timeout_ms: Timeout in ms
*
* Try waiting for the sink to finish updating its payload table by polling for
* the ACT handled bit of DP_PAYLOAD_TABLE_UPDATE_STATUS for up to @timeout_ms
* milliseconds, defaulting to 3000 ms if 0.
*
* Returns:
* 0 if the ACT was handled in time, negative error code on failure.
*/
int drm_dp_dpcd_poll_act_handled(struct drm_dp_aux *aux, int timeout_ms)
{
int ret, status;
/* default to 3 seconds, this is arbitrary */
timeout_ms = timeout_ms ?: 3000;
ret = readx_poll_timeout(read_payload_update_status, aux, status,
status & DP_PAYLOAD_ACT_HANDLED || status < 0,
200, timeout_ms * USEC_PER_MSEC);
if (ret < 0 && status >= 0) {
drm_err(aux->drm_dev, "Failed to get ACT after %d ms, last status: %02x\n",
timeout_ms, status);
return -EINVAL;
} else if (status < 0) {
/*
* Failure here isn't unexpected - the hub may have
* just been unplugged
*/
drm_dbg_kms(aux->drm_dev, "Failed to read payload table status: %d\n", status);
return status;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_dpcd_poll_act_handled);
static bool is_edid_digital_input_dp(const struct drm_edid *drm_edid)
{
/* FIXME: get rid of drm_edid_raw() */
const struct edid *edid = drm_edid_raw(drm_edid);
return edid && edid->revision >= 4 &&
edid->input & DRM_EDID_INPUT_DIGITAL &&
(edid->input & DRM_EDID_DIGITAL_TYPE_MASK) == DRM_EDID_DIGITAL_TYPE_DP;
}
/**
* drm_dp_downstream_is_type() - is the downstream facing port of certain type?
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
* @type: port type to be checked. Can be:
* %DP_DS_PORT_TYPE_DP, %DP_DS_PORT_TYPE_VGA, %DP_DS_PORT_TYPE_DVI,
* %DP_DS_PORT_TYPE_HDMI, %DP_DS_PORT_TYPE_NON_EDID,
* %DP_DS_PORT_TYPE_DP_DUALMODE or %DP_DS_PORT_TYPE_WIRELESS.
*
* Caveat: Only works with DPCD 1.1+ port caps.
*
* Returns: whether the downstream facing port matches the type.
*/
bool drm_dp_downstream_is_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4], u8 type)
{
return drm_dp_is_branch(dpcd) &&
dpcd[DP_DPCD_REV] >= 0x11 &&
(port_cap[0] & DP_DS_PORT_TYPE_MASK) == type;
}
EXPORT_SYMBOL(drm_dp_downstream_is_type);
/**
* drm_dp_downstream_is_tmds() - is the downstream facing port TMDS?
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
* @drm_edid: EDID
*
* Returns: whether the downstream facing port is TMDS (HDMI/DVI).
*/
bool drm_dp_downstream_is_tmds(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4],
const struct drm_edid *drm_edid)
{
if (dpcd[DP_DPCD_REV] < 0x11) {
switch (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_TYPE_MASK) {
case DP_DWN_STRM_PORT_TYPE_TMDS:
return true;
default:
return false;
}
}
switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_DP_DUALMODE:
if (is_edid_digital_input_dp(drm_edid))
return false;
fallthrough;
case DP_DS_PORT_TYPE_DVI:
case DP_DS_PORT_TYPE_HDMI:
return true;
default:
return false;
}
}
EXPORT_SYMBOL(drm_dp_downstream_is_tmds);
/**
* drm_dp_send_real_edid_checksum() - send back real edid checksum value
* @aux: DisplayPort AUX channel
* @real_edid_checksum: real edid checksum for the last block
*
* Returns:
* True on success
*/
bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
u8 real_edid_checksum)
{
u8 link_edid_read = 0, auto_test_req = 0, test_resp = 0;
if (drm_dp_dpcd_read_byte(aux, DP_DEVICE_SERVICE_IRQ_VECTOR,
&auto_test_req) < 0) {
drm_err(aux->drm_dev, "%s: DPCD failed read at register 0x%x\n",
aux->name, DP_DEVICE_SERVICE_IRQ_VECTOR);
return false;
}
auto_test_req &= DP_AUTOMATED_TEST_REQUEST;
if (drm_dp_dpcd_read_byte(aux, DP_TEST_REQUEST, &link_edid_read) < 0) {
drm_err(aux->drm_dev, "%s: DPCD failed read at register 0x%x\n",
aux->name, DP_TEST_REQUEST);
return false;
}
link_edid_read &= DP_TEST_LINK_EDID_READ;
if (!auto_test_req || !link_edid_read) {
drm_dbg_kms(aux->drm_dev, "%s: Source DUT does not support TEST_EDID_READ\n",
aux->name);
return false;
}
if (drm_dp_dpcd_write_byte(aux, DP_DEVICE_SERVICE_IRQ_VECTOR,
auto_test_req) < 0) {
drm_err(aux->drm_dev, "%s: DPCD failed write at register 0x%x\n",
aux->name, DP_DEVICE_SERVICE_IRQ_VECTOR);
return false;
}
/* send back checksum for the last edid extension block data */
if (drm_dp_dpcd_write_byte(aux, DP_TEST_EDID_CHECKSUM,
real_edid_checksum) < 0) {
drm_err(aux->drm_dev, "%s: DPCD failed write at register 0x%x\n",
aux->name, DP_TEST_EDID_CHECKSUM);
return false;
}
test_resp |= DP_TEST_EDID_CHECKSUM_WRITE;
if (drm_dp_dpcd_write_byte(aux, DP_TEST_RESPONSE, test_resp) < 0) {
drm_err(aux->drm_dev, "%s: DPCD failed write at register 0x%x\n",
aux->name, DP_TEST_RESPONSE);
return false;
}
return true;
}
EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
static u8 drm_dp_downstream_port_count(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
{
u8 port_count = dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_PORT_COUNT_MASK;
if (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE && port_count > 4)
port_count = 4;
return port_count;
}
static int drm_dp_read_extended_dpcd_caps(struct drm_dp_aux *aux,
u8 dpcd[DP_RECEIVER_CAP_SIZE])
{
u8 dpcd_ext[DP_RECEIVER_CAP_SIZE];
int ret;
/*
* Prior to DP1.3 the bit represented by
* DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved.
* If it is set DP_DPCD_REV at 0000h could be at a value less than
* the true capability of the panel. The only way to check is to
* then compare 0000h and 2200h.
*/
if (!(dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT))
return 0;
ret = drm_dp_dpcd_read_data(aux, DP_DP13_DPCD_REV, &dpcd_ext,
sizeof(dpcd_ext));
if (ret < 0)
return ret;
if (dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) {
drm_dbg_kms(aux->drm_dev,
"%s: Extended DPCD rev less than base DPCD rev (%d > %d)\n",
aux->name, dpcd[DP_DPCD_REV], dpcd_ext[DP_DPCD_REV]);
return 0;
}
if (!memcmp(dpcd, dpcd_ext, sizeof(dpcd_ext)))
return 0;
drm_dbg_kms(aux->drm_dev, "%s: Base DPCD: %*ph\n", aux->name, DP_RECEIVER_CAP_SIZE, dpcd);
memcpy(dpcd, dpcd_ext, sizeof(dpcd_ext));
return 0;
}
/**
* drm_dp_read_dpcd_caps() - read DPCD caps and extended DPCD caps if
* available
* @aux: DisplayPort AUX channel
* @dpcd: Buffer to store the resulting DPCD in
*
* Attempts to read the base DPCD caps for @aux. Additionally, this function
* checks for and reads the extended DPRX caps (%DP_DP13_DPCD_REV) if
* present.
*
* Returns: %0 if the DPCD was read successfully, negative error code
* otherwise.
*/
int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux,
u8 dpcd[DP_RECEIVER_CAP_SIZE])
{
int ret;
ret = drm_dp_dpcd_read_data(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
if (ret < 0)
return ret;
if (dpcd[DP_DPCD_REV] == 0)
return -EIO;
ret = drm_dp_read_extended_dpcd_caps(aux, dpcd);
if (ret < 0)
return ret;
drm_dbg_kms(aux->drm_dev, "%s: DPCD: %*ph\n", aux->name, DP_RECEIVER_CAP_SIZE, dpcd);
return ret;
}
EXPORT_SYMBOL(drm_dp_read_dpcd_caps);
/**
* drm_dp_read_downstream_info() - read DPCD downstream port info if available
* @aux: DisplayPort AUX channel
* @dpcd: A cached copy of the port's DPCD
* @downstream_ports: buffer to store the downstream port info in
*
* See also:
* drm_dp_downstream_max_clock()
* drm_dp_downstream_max_bpc()
*
* Returns: 0 if either the downstream port info was read successfully or
* there was no downstream info to read, or a negative error code otherwise.
*/
int drm_dp_read_downstream_info(struct drm_dp_aux *aux,
const u8 dpcd[DP_RECEIVER_CAP_SIZE],
u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS])
{
int ret;
u8 len;
memset(downstream_ports, 0, DP_MAX_DOWNSTREAM_PORTS);
/* No downstream info to read */
if (!drm_dp_is_branch(dpcd) || dpcd[DP_DPCD_REV] == DP_DPCD_REV_10)
return 0;
/* Some branches advertise having 0 downstream ports, despite also advertising they have a
* downstream port present. The DP spec isn't clear on if this is allowed or not, but since
* some branches do it we need to handle it regardless.
*/
len = drm_dp_downstream_port_count(dpcd);
if (!len)
return 0;
if (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE)
len *= 4;
ret = drm_dp_dpcd_read_data(aux, DP_DOWNSTREAM_PORT_0, downstream_ports, len);
if (ret < 0)
return ret;
drm_dbg_kms(aux->drm_dev, "%s: DPCD DFP: %*ph\n", aux->name, len, downstream_ports);
return 0;
}
EXPORT_SYMBOL(drm_dp_read_downstream_info);
/**
* drm_dp_downstream_max_dotclock() - extract downstream facing port max dot clock
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
*
* Returns: Downstream facing port max dot clock in kHz on success,
* or 0 if max clock not defined
*/
int drm_dp_downstream_max_dotclock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4])
{
if (!drm_dp_is_branch(dpcd))
return 0;
if (dpcd[DP_DPCD_REV] < 0x11)
return 0;
switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_VGA:
if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
return 0;
return port_cap[1] * 8000;
default:
return 0;
}
}
EXPORT_SYMBOL(drm_dp_downstream_max_dotclock);
/**
* drm_dp_downstream_max_tmds_clock() - extract downstream facing port max TMDS clock
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
* @drm_edid: EDID
*
* Returns: HDMI/DVI downstream facing port max TMDS clock in kHz on success,
* or 0 if max TMDS clock not defined
*/
int drm_dp_downstream_max_tmds_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4],
const struct drm_edid *drm_edid)
{
if (!drm_dp_is_branch(dpcd))
return 0;
if (dpcd[DP_DPCD_REV] < 0x11) {
switch (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_TYPE_MASK) {
case DP_DWN_STRM_PORT_TYPE_TMDS:
return 165000;
default:
return 0;
}
}
switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_DP_DUALMODE:
if (is_edid_digital_input_dp(drm_edid))
return 0;
/*
* It's left up to the driver to check the
* DP dual mode adapter's max TMDS clock.
*
* Unfortunately it looks like branch devices
* may not fordward that the DP dual mode i2c
* access so we just usually get i2c nak :(
*/
fallthrough;
case DP_DS_PORT_TYPE_HDMI:
/*
* We should perhaps assume 165 MHz when detailed cap
* info is not available. But looks like many typical
* branch devices fall into that category and so we'd
* probably end up with users complaining that they can't
* get high resolution modes with their favorite dongle.
*
* So let's limit to 300 MHz instead since DPCD 1.4
* HDMI 2.0 DFPs are required to have the detailed cap
* info. So it's more likely we're dealing with a HDMI 1.4
* compatible* device here.
*/
if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
return 300000;
return port_cap[1] * 2500;
case DP_DS_PORT_TYPE_DVI:
if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
return 165000;
/* FIXME what to do about DVI dual link? */
return port_cap[1] * 2500;
default:
return 0;
}
}
EXPORT_SYMBOL(drm_dp_downstream_max_tmds_clock);
/**
* drm_dp_downstream_min_tmds_clock() - extract downstream facing port min TMDS clock
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
* @drm_edid: EDID
*
* Returns: HDMI/DVI downstream facing port min TMDS clock in kHz on success,
* or 0 if max TMDS clock not defined
*/
int drm_dp_downstream_min_tmds_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4],
const struct drm_edid *drm_edid)
{
if (!drm_dp_is_branch(dpcd))
return 0;
if (dpcd[DP_DPCD_REV] < 0x11) {
switch (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_TYPE_MASK) {
case DP_DWN_STRM_PORT_TYPE_TMDS:
return 25000;
default:
return 0;
}
}
switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_DP_DUALMODE:
if (is_edid_digital_input_dp(drm_edid))
return 0;
fallthrough;
case DP_DS_PORT_TYPE_DVI:
case DP_DS_PORT_TYPE_HDMI:
/*
* Unclear whether the protocol converter could
* utilize pixel replication. Assume it won't.
*/
return 25000;
default:
return 0;
}
}
EXPORT_SYMBOL(drm_dp_downstream_min_tmds_clock);
/**
* drm_dp_downstream_max_bpc() - extract downstream facing port max
* bits per component
* @dpcd: DisplayPort configuration data
* @port_cap: downstream facing port capabilities
* @drm_edid: EDID
*
* Returns: Max bpc on success or 0 if max bpc not defined
*/
int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4],
const struct drm_edid *drm_edid)
{
if (!drm_dp_is_branch(dpcd))
return 0;
if (dpcd[DP_DPCD_REV] < 0x11) {
switch (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_TYPE_MASK) {
case DP_DWN_STRM_PORT_TYPE_DP:
return 0;
default:
return 8;
}
}
switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_DP:
return 0;
case DP_DS_PORT_TYPE_DP_DUALMODE:
if (is_edid_digital_input_dp(drm_edid))
return 0;
fallthrough;
case DP_DS_PORT_TYPE_HDMI:
case DP_DS_PORT_TYPE_DVI:
case DP_DS_PORT_TYPE_VGA:
if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
return 8;
switch (port_cap[2] & DP_DS_MAX_BPC_MASK) {
case DP_DS_8BPC:
return 8;
case DP_DS_10BPC:
return 10;
case DP_DS_12BPC:
return 12;
case DP_DS_16BPC:
return 16;
default:
return 8;
}
break;
default:
return 8;
}
}
EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
/**
* drm_dp_downstream_420_passthrough() - determine downstream facing port
* YCbCr 4:2:0 pass-through capability
* @dpcd: DisplayPort configuration data
* @port_cap: downstream facing port capabilities
*
* Returns: whether the downstream facing port can pass through YCbCr 4:2:0
*/
bool drm_dp_downstream_420_passthrough(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4])
{
if (!drm_dp_is_branch(dpcd))
return false;
if (dpcd[DP_DPCD_REV] < 0x13)
return false;
switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_DP:
return true;
case DP_DS_PORT_TYPE_HDMI:
if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
return false;
return port_cap[3] & DP_DS_HDMI_YCBCR420_PASS_THROUGH;
default:
return false;
}
}
EXPORT_SYMBOL(drm_dp_downstream_420_passthrough);
/**
* drm_dp_downstream_444_to_420_conversion() - determine downstream facing port
* YCbCr 4:4:4->4:2:0 conversion capability
* @dpcd: DisplayPort configuration data
* @port_cap: downstream facing port capabilities
*
* Returns: whether the downstream facing port can convert YCbCr 4:4:4 to 4:2:0
*/
bool drm_dp_downstream_444_to_420_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4])
{
if (!drm_dp_is_branch(dpcd))
return false;
if (dpcd[DP_DPCD_REV] < 0x13)
return false;
switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_HDMI:
if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
return false;
return port_cap[3] & DP_DS_HDMI_YCBCR444_TO_420_CONV;
default:
return false;
}
}
EXPORT_SYMBOL(drm_dp_downstream_444_to_420_conversion);
/**
* drm_dp_downstream_rgb_to_ycbcr_conversion() - determine downstream facing port
* RGB->YCbCr conversion capability
* @dpcd: DisplayPort configuration data
* @port_cap: downstream facing port capabilities
* @color_spc: Colorspace for which conversion cap is sought
*
* Returns: whether the downstream facing port can convert RGB->YCbCr for a given
* colorspace.
*/
bool drm_dp_downstream_rgb_to_ycbcr_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4],
u8 color_spc)
{
if (!drm_dp_is_branch(dpcd))
return false;
if (dpcd[DP_DPCD_REV] < 0x13)
return false;
switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_HDMI:
if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
return false;
return port_cap[3] & color_spc;
default:
return false;
}
}
EXPORT_SYMBOL(drm_dp_downstream_rgb_to_ycbcr_conversion);
/**
* drm_dp_downstream_mode() - return a mode for downstream facing port
* @dev: DRM device
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
*
* Provides a suitable mode for downstream facing ports without EDID.
*
* Returns: A new drm_display_mode on success or NULL on failure
*/
struct drm_display_mode *
drm_dp_downstream_mode(struct drm_device *dev,
const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4])
{
u8 vic;
if (!drm_dp_is_branch(dpcd))
return NULL;
if (dpcd[DP_DPCD_REV] < 0x11)
return NULL;
switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_NON_EDID:
switch (port_cap[0] & DP_DS_NON_EDID_MASK) {
case DP_DS_NON_EDID_720x480i_60:
vic = 6;
break;
case DP_DS_NON_EDID_720x480i_50:
vic = 21;
break;
case DP_DS_NON_EDID_1920x1080i_60:
vic = 5;
break;
case DP_DS_NON_EDID_1920x1080i_50:
vic = 20;
break;
case DP_DS_NON_EDID_1280x720_60:
vic = 4;
break;
case DP_DS_NON_EDID_1280x720_50:
vic = 19;
break;
default:
return NULL;
}
return drm_display_mode_from_cea_vic(dev, vic);
default:
return NULL;
}
}
EXPORT_SYMBOL(drm_dp_downstream_mode);
/**
* drm_dp_downstream_id() - identify branch device
* @aux: DisplayPort AUX channel
* @id: DisplayPort branch device id
*
* Returns branch device id on success or NULL on failure
*/
int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6])
{
return drm_dp_dpcd_read_data(aux, DP_BRANCH_ID, id, 6);
}
EXPORT_SYMBOL(drm_dp_downstream_id);
/**
* drm_dp_downstream_debug() - debug DP branch devices
* @m: pointer for debugfs file
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
* @drm_edid: EDID
* @aux: DisplayPort AUX channel
*
*/
void drm_dp_downstream_debug(struct seq_file *m,
const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4],
const struct drm_edid *drm_edid,
struct drm_dp_aux *aux)
{
bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
DP_DETAILED_CAP_INFO_AVAILABLE;
int clk;
int bpc;
char id[7];
int len;
uint8_t rev[2];
int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
bool branch_device = drm_dp_is_branch(dpcd);
seq_printf(m, "\tDP branch device present: %s\n",
str_yes_no(branch_device));
if (!branch_device)
return;
switch (type) {
case DP_DS_PORT_TYPE_DP:
seq_puts(m, "\t\tType: DisplayPort\n");
break;
case DP_DS_PORT_TYPE_VGA:
seq_puts(m, "\t\tType: VGA\n");
break;
case DP_DS_PORT_TYPE_DVI:
seq_puts(m, "\t\tType: DVI\n");
break;
case DP_DS_PORT_TYPE_HDMI:
seq_puts(m, "\t\tType: HDMI\n");
break;
case DP_DS_PORT_TYPE_NON_EDID:
seq_puts(m, "\t\tType: others without EDID support\n");
break;
case DP_DS_PORT_TYPE_DP_DUALMODE:
seq_puts(m, "\t\tType: DP++\n");
break;
case DP_DS_PORT_TYPE_WIRELESS:
seq_puts(m, "\t\tType: Wireless\n");
break;
default:
seq_puts(m, "\t\tType: N/A\n");
}
memset(id, 0, sizeof(id));
drm_dp_downstream_id(aux, id);
seq_printf(m, "\t\tID: %s\n", id);
len = drm_dp_dpcd_read_data(aux, DP_BRANCH_HW_REV, &rev[0], 1);
if (!len)
seq_printf(m, "\t\tHW: %d.%d\n",
(rev[0] & 0xf0) >> 4, rev[0] & 0xf);
len = drm_dp_dpcd_read_data(aux, DP_BRANCH_SW_REV, rev, 2);
if (!len)
seq_printf(m, "\t\tSW: %d.%d\n", rev[0], rev[1]);
if (detailed_cap_info) {
clk = drm_dp_downstream_max_dotclock(dpcd, port_cap);
if (clk > 0)
seq_printf(m, "\t\tMax dot clock: %d kHz\n", clk);
clk = drm_dp_downstream_max_tmds_clock(dpcd, port_cap, drm_edid);
if (clk > 0)
seq_printf(m, "\t\tMax TMDS clock: %d kHz\n", clk);
clk = drm_dp_downstream_min_tmds_clock(dpcd, port_cap, drm_edid);
if (clk > 0)
seq_printf(m, "\t\tMin TMDS clock: %d kHz\n", clk);
bpc = drm_dp_downstream_max_bpc(dpcd, port_cap, drm_edid);
if (bpc > 0)
seq_printf(m, "\t\tMax bpc: %d\n", bpc);
}
}
EXPORT_SYMBOL(drm_dp_downstream_debug);
/**
* drm_dp_subconnector_type() - get DP branch device type
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
*/
enum drm_mode_subconnector
drm_dp_subconnector_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4])
{
int type;
if (!drm_dp_is_branch(dpcd))
return DRM_MODE_SUBCONNECTOR_Native;
/* DP 1.0 approach */
if (dpcd[DP_DPCD_REV] == DP_DPCD_REV_10) {
type = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
DP_DWN_STRM_PORT_TYPE_MASK;
switch (type) {
case DP_DWN_STRM_PORT_TYPE_TMDS:
/* Can be HDMI or DVI-D, DVI-D is a safer option */
return DRM_MODE_SUBCONNECTOR_DVID;
case DP_DWN_STRM_PORT_TYPE_ANALOG:
/* Can be VGA or DVI-A, VGA is more popular */
return DRM_MODE_SUBCONNECTOR_VGA;
case DP_DWN_STRM_PORT_TYPE_DP:
return DRM_MODE_SUBCONNECTOR_DisplayPort;
case DP_DWN_STRM_PORT_TYPE_OTHER:
default:
return DRM_MODE_SUBCONNECTOR_Unknown;
}
}
type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
switch (type) {
case DP_DS_PORT_TYPE_DP:
case DP_DS_PORT_TYPE_DP_DUALMODE:
return DRM_MODE_SUBCONNECTOR_DisplayPort;
case DP_DS_PORT_TYPE_VGA:
return DRM_MODE_SUBCONNECTOR_VGA;
case DP_DS_PORT_TYPE_DVI:
return DRM_MODE_SUBCONNECTOR_DVID;
case DP_DS_PORT_TYPE_HDMI:
return DRM_MODE_SUBCONNECTOR_HDMIA;
case DP_DS_PORT_TYPE_WIRELESS:
return DRM_MODE_SUBCONNECTOR_Wireless;
case DP_DS_PORT_TYPE_NON_EDID:
default:
return DRM_MODE_SUBCONNECTOR_Unknown;
}
}
EXPORT_SYMBOL(drm_dp_subconnector_type);
/**
* drm_dp_set_subconnector_property - set subconnector for DP connector
* @connector: connector to set property on
* @status: connector status
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
*
* Called by a driver on every detect event.
*/
void drm_dp_set_subconnector_property(struct drm_connector *connector,
enum drm_connector_status status,
const u8 *dpcd,
const u8 port_cap[4])
{
enum drm_mode_subconnector subconnector = DRM_MODE_SUBCONNECTOR_Unknown;
if (status == connector_status_connected)
subconnector = drm_dp_subconnector_type(dpcd, port_cap);
drm_object_property_set_value(&connector->base,
connector->dev->mode_config.dp_subconnector_property,
subconnector);
}
EXPORT_SYMBOL(drm_dp_set_subconnector_property);
/**
* drm_dp_read_sink_count_cap() - Check whether a given connector has a valid sink
* count
* @connector: The DRM connector to check
* @dpcd: A cached copy of the connector's DPCD RX capabilities
* @desc: A cached copy of the connector's DP descriptor
*
* See also: drm_dp_read_sink_count()
*
* Returns: %True if the (e)DP connector has a valid sink count that should
* be probed, %false otherwise.
*/
bool drm_dp_read_sink_count_cap(struct drm_connector *connector,
const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const struct drm_dp_desc *desc)
{
/* Some eDP panels don't set a valid value for the sink count */
return connector->connector_type != DRM_MODE_CONNECTOR_eDP &&
dpcd[DP_DPCD_REV] >= DP_DPCD_REV_11 &&
dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT &&
!drm_dp_has_quirk(desc, DP_DPCD_QUIRK_NO_SINK_COUNT);
}
EXPORT_SYMBOL(drm_dp_read_sink_count_cap);
/**
* drm_dp_read_sink_count() - Retrieve the sink count for a given sink
* @aux: The DP AUX channel to use
*
* See also: drm_dp_read_sink_count_cap()
*
* Returns: The current sink count reported by @aux, or a negative error code
* otherwise.
*/
int drm_dp_read_sink_count(struct drm_dp_aux *aux)
{
u8 count;
int ret;
ret = drm_dp_dpcd_read_byte(aux, DP_SINK_COUNT, &count);
if (ret < 0)
return ret;
return DP_GET_SINK_COUNT(count);
}
EXPORT_SYMBOL(drm_dp_read_sink_count);
/*
* I2C-over-AUX implementation
*/
static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
I2C_FUNC_SMBUS_READ_BLOCK_DATA |
I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
I2C_FUNC_10BIT_ADDR;
}
static void drm_dp_i2c_msg_write_status_update(struct drm_dp_aux_msg *msg)
{
/*
* In case of i2c defer or short i2c ack reply to a write,
* we need to switch to WRITE_STATUS_UPDATE to drain the
* rest of the message
*/
if ((msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_I2C_WRITE) {
msg->request &= DP_AUX_I2C_MOT;
msg->request |= DP_AUX_I2C_WRITE_STATUS_UPDATE;
}
}
#define AUX_PRECHARGE_LEN 10 /* 10 to 16 */
#define AUX_SYNC_LEN (16 + 4) /* preamble + AUX_SYNC_END */
#define AUX_STOP_LEN 4
#define AUX_CMD_LEN 4
#define AUX_ADDRESS_LEN 20
#define AUX_REPLY_PAD_LEN 4
#define AUX_LENGTH_LEN 8
/*
* Calculate the duration of the AUX request/reply in usec. Gives the
* "best" case estimate, ie. successful while as short as possible.
*/
static int drm_dp_aux_req_duration(const struct drm_dp_aux_msg *msg)
{
int len = AUX_PRECHARGE_LEN + AUX_SYNC_LEN + AUX_STOP_LEN +
AUX_CMD_LEN + AUX_ADDRESS_LEN + AUX_LENGTH_LEN;
if ((msg->request & DP_AUX_I2C_READ) == 0)
len += msg->size * 8;
return len;
}
static int drm_dp_aux_reply_duration(const struct drm_dp_aux_msg *msg)
{
int len = AUX_PRECHARGE_LEN + AUX_SYNC_LEN + AUX_STOP_LEN +
AUX_CMD_LEN + AUX_REPLY_PAD_LEN;
/*
* For read we expect what was asked. For writes there will
* be 0 or 1 data bytes. Assume 0 for the "best" case.
*/
if (msg->request & DP_AUX_I2C_READ)
len += msg->size * 8;
return len;
}
#define I2C_START_LEN 1
#define I2C_STOP_LEN 1
#define I2C_ADDR_LEN 9 /* ADDRESS + R/W + ACK/NACK */
#define I2C_DATA_LEN 9 /* DATA + ACK/NACK */
/*
* Calculate the length of the i2c transfer in usec, assuming
* the i2c bus speed is as specified. Gives the "worst"
* case estimate, ie. successful while as long as possible.
* Doesn't account the "MOT" bit, and instead assumes each
* message includes a START, ADDRESS and STOP. Neither does it
* account for additional random variables such as clock stretching.
*/
static int drm_dp_i2c_msg_duration(const struct drm_dp_aux_msg *msg,
int i2c_speed_khz)
{
/* AUX bitrate is 1MHz, i2c bitrate as specified */
return DIV_ROUND_UP((I2C_START_LEN + I2C_ADDR_LEN +
msg->size * I2C_DATA_LEN +
I2C_STOP_LEN) * 1000, i2c_speed_khz);
}
/*
* Determine how many retries should be attempted to successfully transfer
* the specified message, based on the estimated durations of the
* i2c and AUX transfers.
*/
static int drm_dp_i2c_retry_count(const struct drm_dp_aux_msg *msg,
int i2c_speed_khz)
{
int aux_time_us = drm_dp_aux_req_duration(msg) +
drm_dp_aux_reply_duration(msg);
int i2c_time_us = drm_dp_i2c_msg_duration(msg, i2c_speed_khz);
return DIV_ROUND_UP(i2c_time_us, aux_time_us + AUX_RETRY_INTERVAL);
}
/*
* FIXME currently assumes 10 kHz as some real world devices seem
* to require it. We should query/set the speed via DPCD if supported.
*/
static int dp_aux_i2c_speed_khz __read_mostly = 10;
module_param_unsafe(dp_aux_i2c_speed_khz, int, 0644);
MODULE_PARM_DESC(dp_aux_i2c_speed_khz,
"Assumed speed of the i2c bus in kHz, (1-400, default 10)");
/*
* Transfer a single I2C-over-AUX message and handle various error conditions,
* retrying the transaction as appropriate. It is assumed that the
* &drm_dp_aux.transfer function does not modify anything in the msg other than the
* reply field.
*
* Returns bytes transferred on success, or a negative error code on failure.
*/
static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
{
unsigned int retry, defer_i2c;
int ret;
/*
* DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device
* is required to retry at least seven times upon receiving AUX_DEFER
* before giving up the AUX transaction.
*
* We also try to account for the i2c bus speed.
*/
int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
ret = aux->transfer(aux, msg);
if (ret < 0) {
if (ret == -EBUSY)
continue;
/*
* While timeouts can be errors, they're usually normal
* behavior (for instance, when a driver tries to
* communicate with a non-existent DisplayPort device).
* Avoid spamming the kernel log with timeout errors.
*/
if (ret == -ETIMEDOUT)
drm_dbg_kms_ratelimited(aux->drm_dev, "%s: transaction timed out\n",
aux->name);
else
drm_dbg_kms(aux->drm_dev, "%s: transaction failed: %d\n",
aux->name, ret);
return ret;
}
switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) {
case DP_AUX_NATIVE_REPLY_ACK:
/*
* For I2C-over-AUX transactions this isn't enough, we
* need to check for the I2C ACK reply.
*/
break;
case DP_AUX_NATIVE_REPLY_NACK:
drm_dbg_kms(aux->drm_dev, "%s: native nack (result=%d, size=%zu)\n",
aux->name, ret, msg->size);
return -EREMOTEIO;
case DP_AUX_NATIVE_REPLY_DEFER:
drm_dbg_kms(aux->drm_dev, "%s: native defer\n", aux->name);
/*
* We could check for I2C bit rate capabilities and if
* available adjust this interval. We could also be
* more careful with DP-to-legacy adapters where a
* long legacy cable may force very low I2C bit rates.
*
* For now just defer for long enough to hopefully be
* safe for all use-cases.
*/
usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);
continue;
default:
drm_err(aux->drm_dev, "%s: invalid native reply %#04x\n",
aux->name, msg->reply);
return -EREMOTEIO;
}
switch (msg->reply & DP_AUX_I2C_REPLY_MASK) {
case DP_AUX_I2C_REPLY_ACK:
/*
* Both native ACK and I2C ACK replies received. We
* can assume the transfer was successful.
*/
if (ret != msg->size)
drm_dp_i2c_msg_write_status_update(msg);
return ret;
case DP_AUX_I2C_REPLY_NACK:
drm_dbg_kms(aux->drm_dev, "%s: I2C nack (result=%d, size=%zu)\n",
aux->name, ret, msg->size);
aux->i2c_nack_count++;
return -EREMOTEIO;
case DP_AUX_I2C_REPLY_DEFER:
drm_dbg_kms(aux->drm_dev, "%s: I2C defer\n", aux->name);
/* DP Compliance Test 4.2.2.5 Requirement:
* Must have at least 7 retries for I2C defers on the
* transaction to pass this test
*/
aux->i2c_defer_count++;
if (defer_i2c < 7)
defer_i2c++;
usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);
drm_dp_i2c_msg_write_status_update(msg);
continue;
default:
drm_err(aux->drm_dev, "%s: invalid I2C reply %#04x\n",
aux->name, msg->reply);
return -EREMOTEIO;
}
}
drm_dbg_kms(aux->drm_dev, "%s: Too many retries, giving up\n", aux->name);
return -EREMOTEIO;
}
static void drm_dp_i2c_msg_set_request(struct drm_dp_aux_msg *msg,
const struct i2c_msg *i2c_msg)
{
msg->request = (i2c_msg->flags & I2C_M_RD) ?
DP_AUX_I2C_READ : DP_AUX_I2C_WRITE;
if (!(i2c_msg->flags & I2C_M_STOP))
msg->request |= DP_AUX_I2C_MOT;
}
/*
* Keep retrying drm_dp_i2c_do_msg until all data has been transferred.
*
* Returns an error code on failure, or a recommended transfer size on success.
*/
static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *orig_msg)
{
int err, ret = orig_msg->size;
struct drm_dp_aux_msg msg = *orig_msg;
while (msg.size > 0) {
err = drm_dp_i2c_do_msg(aux, &msg);
if (err <= 0)
return err == 0 ? -EPROTO : err;
if (err < msg.size && err < ret) {
drm_dbg_kms(aux->drm_dev,
"%s: Partial I2C reply: requested %zu bytes got %d bytes\n",
aux->name, msg.size, err);
ret = err;
}
msg.size -= err;
msg.buffer += err;
}
return ret;
}
/*
* Bizlink designed DP->DVI-D Dual Link adapters require the I2C over AUX
* packets to be as large as possible. If not, the I2C transactions never
* succeed. Hence the default is maximum.
*/
static int dp_aux_i2c_transfer_size __read_mostly = DP_AUX_MAX_PAYLOAD_BYTES;
module_param_unsafe(dp_aux_i2c_transfer_size, int, 0644);
MODULE_PARM_DESC(dp_aux_i2c_transfer_size,
"Number of bytes to transfer in a single I2C over DP AUX CH message, (1-16, default 16)");
static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
int num)
{
struct drm_dp_aux *aux = adapter->algo_data;
unsigned int i, j;
unsigned transfer_size;
struct drm_dp_aux_msg msg;
int err = 0;
if (aux->powered_down)
return -EBUSY;
dp_aux_i2c_transfer_size = clamp(dp_aux_i2c_transfer_size, 1, DP_AUX_MAX_PAYLOAD_BYTES);
memset(&msg, 0, sizeof(msg));
for (i = 0; i < num; i++) {
msg.address = msgs[i].addr;
if (!aux->no_zero_sized) {
drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
/* Send a bare address packet to start the transaction.
* Zero sized messages specify an address only (bare
* address) transaction.
*/
msg.buffer = NULL;
msg.size = 0;
err = drm_dp_i2c_do_msg(aux, &msg);
}
/*
* Reset msg.request in case in case it got
* changed into a WRITE_STATUS_UPDATE.
*/
drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
if (err < 0)
break;
/* We want each transaction to be as large as possible, but
* we'll go to smaller sizes if the hardware gives us a
* short reply.
*/
transfer_size = dp_aux_i2c_transfer_size;
for (j = 0; j < msgs[i].len; j += msg.size) {
msg.buffer = msgs[i].buf + j;
msg.size = min(transfer_size, msgs[i].len - j);
if (j + msg.size == msgs[i].len && aux->no_zero_sized)
msg.request &= ~DP_AUX_I2C_MOT;
err = drm_dp_i2c_drain_msg(aux, &msg);
/*
* Reset msg.request in case in case it got
* changed into a WRITE_STATUS_UPDATE.
*/
drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
if (err < 0)
break;
transfer_size = err;
}
if (err < 0)
break;
}
if (err >= 0)
err = num;
if (!aux->no_zero_sized) {
/* Send a bare address packet to close out the transaction.
* Zero sized messages specify an address only (bare
* address) transaction.
*/
msg.request &= ~DP_AUX_I2C_MOT;
msg.buffer = NULL;
msg.size = 0;
(void)drm_dp_i2c_do_msg(aux, &msg);
}
return err;
}
static const struct i2c_algorithm drm_dp_i2c_algo = {
.functionality = drm_dp_i2c_functionality,
.master_xfer = drm_dp_i2c_xfer,
};
static struct drm_dp_aux *i2c_to_aux(struct i2c_adapter *i2c)
{
return container_of(i2c, struct drm_dp_aux, ddc);
}
static void lock_bus(struct i2c_adapter *i2c, unsigned int flags)
{
mutex_lock(&i2c_to_aux(i2c)->hw_mutex);
}
static int trylock_bus(struct i2c_adapter *i2c, unsigned int flags)
{
return mutex_trylock(&i2c_to_aux(i2c)->hw_mutex);
}
static void unlock_bus(struct i2c_adapter *i2c, unsigned int flags)
{
mutex_unlock(&i2c_to_aux(i2c)->hw_mutex);
}
static const struct i2c_lock_operations drm_dp_i2c_lock_ops = {
.lock_bus = lock_bus,
.trylock_bus = trylock_bus,
.unlock_bus = unlock_bus,
};
static int drm_dp_aux_get_crc(struct drm_dp_aux *aux, u8 *crc)
{
u8 buf, count;
int ret;
ret = drm_dp_dpcd_read_byte(aux, DP_TEST_SINK, &buf);
if (ret < 0)
return ret;
WARN_ON(!(buf & DP_TEST_SINK_START));
ret = drm_dp_dpcd_read_byte(aux, DP_TEST_SINK_MISC, &buf);
if (ret < 0)
return ret;
count = buf & DP_TEST_COUNT_MASK;
if (count == aux->crc_count)
return -EAGAIN; /* No CRC yet */
aux->crc_count = count;
/*
* At DP_TEST_CRC_R_CR, there's 6 bytes containing CRC data, 2 bytes
* per component (RGB or CrYCb).
*/
return drm_dp_dpcd_read_data(aux, DP_TEST_CRC_R_CR, crc, 6);
}
static void drm_dp_aux_crc_work(struct work_struct *work)
{
struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux,
crc_work);
struct drm_crtc *crtc;
u8 crc_bytes[6];
uint32_t crcs[3];
int ret;
if (WARN_ON(!aux->crtc))
return;
crtc = aux->crtc;
while (crtc->crc.opened) {
drm_crtc_wait_one_vblank(crtc);
if (!crtc->crc.opened)
break;
ret = drm_dp_aux_get_crc(aux, crc_bytes);
if (ret == -EAGAIN) {
usleep_range(1000, 2000);
ret = drm_dp_aux_get_crc(aux, crc_bytes);
}
if (ret == -EAGAIN) {
drm_dbg_kms(aux->drm_dev, "%s: Get CRC failed after retrying: %d\n",
aux->name, ret);
continue;
} else if (ret) {
drm_dbg_kms(aux->drm_dev, "%s: Failed to get a CRC: %d\n", aux->name, ret);
continue;
}
crcs[0] = crc_bytes[0] | crc_bytes[1] << 8;
crcs[1] = crc_bytes[2] | crc_bytes[3] << 8;
crcs[2] = crc_bytes[4] | crc_bytes[5] << 8;
drm_crtc_add_crc_entry(crtc, false, 0, crcs);
}
}
/**
* drm_dp_remote_aux_init() - minimally initialise a remote aux channel
* @aux: DisplayPort AUX channel
*
* Used for remote aux channel in general. Merely initialize the crc work
* struct.
*/
void drm_dp_remote_aux_init(struct drm_dp_aux *aux)
{
INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work);
}
EXPORT_SYMBOL(drm_dp_remote_aux_init);
/**
* drm_dp_aux_init() - minimally initialise an aux channel
* @aux: DisplayPort AUX channel
*
* If you need to use the drm_dp_aux's i2c adapter prior to registering it with
* the outside world, call drm_dp_aux_init() first. For drivers which are
* grandparents to their AUX adapters (e.g. the AUX adapter is parented by a
* &drm_connector), you must still call drm_dp_aux_register() once the connector
* has been registered to allow userspace access to the auxiliary DP channel.
* Likewise, for such drivers you should also assign &drm_dp_aux.drm_dev as
* early as possible so that the &drm_device that corresponds to the AUX adapter
* may be mentioned in debugging output from the DRM DP helpers.
*
* For devices which use a separate platform device for their AUX adapters, this
* may be called as early as required by the driver.
*
*/
void drm_dp_aux_init(struct drm_dp_aux *aux)
{
mutex_init(&aux->hw_mutex);
mutex_init(&aux->cec.lock);
INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work);
aux->ddc.algo = &drm_dp_i2c_algo;
aux->ddc.algo_data = aux;
aux->ddc.retries = 3;
aux->ddc.lock_ops = &drm_dp_i2c_lock_ops;
}
EXPORT_SYMBOL(drm_dp_aux_init);
/**
* drm_dp_aux_register() - initialise and register aux channel
* @aux: DisplayPort AUX channel
*
* Automatically calls drm_dp_aux_init() if this hasn't been done yet. This
* should only be called once the parent of @aux, &drm_dp_aux.dev, is
* initialized. For devices which are grandparents of their AUX channels,
* &drm_dp_aux.dev will typically be the &drm_connector &device which
* corresponds to @aux. For these devices, it's advised to call
* drm_dp_aux_register() in &drm_connector_funcs.late_register, and likewise to
* call drm_dp_aux_unregister() in &drm_connector_funcs.early_unregister.
* Functions which don't follow this will likely Oops when
* %CONFIG_DRM_DISPLAY_DP_AUX_CHARDEV is enabled.
*
* For devices where the AUX channel is a device that exists independently of
* the &drm_device that uses it, such as SoCs and bridge devices, it is
* recommended to call drm_dp_aux_register() after a &drm_device has been
* assigned to &drm_dp_aux.drm_dev, and likewise to call
* drm_dp_aux_unregister() once the &drm_device should no longer be associated
* with the AUX channel (e.g. on bridge detach).
*
* Drivers which need to use the aux channel before either of the two points
* mentioned above need to call drm_dp_aux_init() in order to use the AUX
* channel before registration.
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_aux_register(struct drm_dp_aux *aux)
{
int ret;
WARN_ON_ONCE(!aux->drm_dev);
if (!aux->ddc.algo)
drm_dp_aux_init(aux);
aux->ddc.owner = THIS_MODULE;
aux->ddc.dev.parent = aux->dev;
strscpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev),
sizeof(aux->ddc.name));
ret = drm_dp_aux_register_devnode(aux);
if (ret)
return ret;
ret = i2c_add_adapter(&aux->ddc);
if (ret) {
drm_dp_aux_unregister_devnode(aux);
return ret;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_aux_register);
/**
* drm_dp_aux_unregister() - unregister an AUX adapter
* @aux: DisplayPort AUX channel
*/
void drm_dp_aux_unregister(struct drm_dp_aux *aux)
{
drm_dp_aux_unregister_devnode(aux);
i2c_del_adapter(&aux->ddc);
}
EXPORT_SYMBOL(drm_dp_aux_unregister);
#define PSR_SETUP_TIME(x) [DP_PSR_SETUP_TIME_ ## x >> DP_PSR_SETUP_TIME_SHIFT] = (x)
/**
* drm_dp_psr_setup_time() - PSR setup in time usec
* @psr_cap: PSR capabilities from DPCD
*
* Returns:
* PSR setup time for the panel in microseconds, negative
* error code on failure.
*/
int drm_dp_psr_setup_time(const u8 psr_cap[EDP_PSR_RECEIVER_CAP_SIZE])
{
static const u16 psr_setup_time_us[] = {
PSR_SETUP_TIME(330),
PSR_SETUP_TIME(275),
PSR_SETUP_TIME(220),
PSR_SETUP_TIME(165),
PSR_SETUP_TIME(110),
PSR_SETUP_TIME(55),
PSR_SETUP_TIME(0),
};
int i;
i = (psr_cap[1] & DP_PSR_SETUP_TIME_MASK) >> DP_PSR_SETUP_TIME_SHIFT;
if (i >= ARRAY_SIZE(psr_setup_time_us))
return -EINVAL;
return psr_setup_time_us[i];
}
EXPORT_SYMBOL(drm_dp_psr_setup_time);
#undef PSR_SETUP_TIME
/**
* drm_dp_start_crc() - start capture of frame CRCs
* @aux: DisplayPort AUX channel
* @crtc: CRTC displaying the frames whose CRCs are to be captured
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_start_crc(struct drm_dp_aux *aux, struct drm_crtc *crtc)
{
u8 buf;
int ret;
ret = drm_dp_dpcd_read_byte(aux, DP_TEST_SINK, &buf);
if (ret < 0)
return ret;
ret = drm_dp_dpcd_write_byte(aux, DP_TEST_SINK, buf | DP_TEST_SINK_START);
if (ret < 0)
return ret;
aux->crc_count = 0;
aux->crtc = crtc;
schedule_work(&aux->crc_work);
return 0;
}
EXPORT_SYMBOL(drm_dp_start_crc);
/**
* drm_dp_stop_crc() - stop capture of frame CRCs
* @aux: DisplayPort AUX channel
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_stop_crc(struct drm_dp_aux *aux)
{
u8 buf;
int ret;
ret = drm_dp_dpcd_read_byte(aux, DP_TEST_SINK, &buf);
if (ret < 0)
return ret;
ret = drm_dp_dpcd_write_byte(aux, DP_TEST_SINK, buf & ~DP_TEST_SINK_START);
if (ret < 0)
return ret;
flush_work(&aux->crc_work);
aux->crtc = NULL;
return 0;
}
EXPORT_SYMBOL(drm_dp_stop_crc);
struct dpcd_quirk {
u8 oui[3];
u8 device_id[6];
bool is_branch;
u32 quirks;
};
#define OUI(first, second, third) { (first), (second), (third) }
#define DEVICE_ID(first, second, third, fourth, fifth, sixth) \
{ (first), (second), (third), (fourth), (fifth), (sixth) }
#define DEVICE_ID_ANY DEVICE_ID(0, 0, 0, 0, 0, 0)
static const struct dpcd_quirk dpcd_quirk_list[] = {
/* Analogix 7737 needs reduced M and N at HBR2 link rates */
{ OUI(0x00, 0x22, 0xb9), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_CONSTANT_N) },
/* LG LP140WF6-SPM1 eDP panel */
{ OUI(0x00, 0x22, 0xb9), DEVICE_ID('s', 'i', 'v', 'a', 'r', 'T'), false, BIT(DP_DPCD_QUIRK_CONSTANT_N) },
/* Apple panels need some additional handling to support PSR */
{ OUI(0x00, 0x10, 0xfa), DEVICE_ID_ANY, false, BIT(DP_DPCD_QUIRK_NO_PSR) },
/* CH7511 seems to leave SINK_COUNT zeroed */
{ OUI(0x00, 0x00, 0x00), DEVICE_ID('C', 'H', '7', '5', '1', '1'), false, BIT(DP_DPCD_QUIRK_NO_SINK_COUNT) },
/* Synaptics DP1.4 MST hubs can support DSC without virtual DPCD */
{ OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) },
/* Synaptics DP1.4 MST hubs require DSC for some modes on which it applies HBLANK expansion. */
{ OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC) },
/* MediaTek panels (at least in U3224KBA) require DSC for modes with a short HBLANK on UHBR links. */
{ OUI(0x00, 0x0C, 0xE7), DEVICE_ID_ANY, false, BIT(DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC) },
/* Apple MacBookPro 2017 15 inch eDP Retina panel reports too low DP_MAX_LINK_RATE */
{ OUI(0x00, 0x10, 0xfa), DEVICE_ID(101, 68, 21, 101, 98, 97), false, BIT(DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS) },
};
#undef OUI
/*
* Get a bit mask of DPCD quirks for the sink/branch device identified by
* ident. The quirk data is shared but it's up to the drivers to act on the
* data.
*
* For now, only the OUI (first three bytes) is used, but this may be extended
* to device identification string and hardware/firmware revisions later.
*/
static u32
drm_dp_get_quirks(const struct drm_dp_dpcd_ident *ident, bool is_branch)
{
const struct dpcd_quirk *quirk;
u32 quirks = 0;
int i;
u8 any_device[] = DEVICE_ID_ANY;
for (i = 0; i < ARRAY_SIZE(dpcd_quirk_list); i++) {
quirk = &dpcd_quirk_list[i];
if (quirk->is_branch != is_branch)
continue;
if (memcmp(quirk->oui, ident->oui, sizeof(ident->oui)) != 0)
continue;
if (memcmp(quirk->device_id, any_device, sizeof(any_device)) != 0 &&
memcmp(quirk->device_id, ident->device_id, sizeof(ident->device_id)) != 0)
continue;
quirks |= quirk->quirks;
}
return quirks;
}
#undef DEVICE_ID_ANY
#undef DEVICE_ID
static int drm_dp_read_ident(struct drm_dp_aux *aux, unsigned int offset,
struct drm_dp_dpcd_ident *ident)
{
return drm_dp_dpcd_read_data(aux, offset, ident, sizeof(*ident));
}
static void drm_dp_dump_desc(struct drm_dp_aux *aux,
const char *device_name, const struct drm_dp_desc *desc)
{
const struct drm_dp_dpcd_ident *ident = &desc->ident;
drm_dbg_kms(aux->drm_dev,
"%s: %s: OUI %*phD dev-ID %*pE HW-rev %d.%d SW-rev %d.%d quirks 0x%04x\n",
aux->name, device_name,
(int)sizeof(ident->oui), ident->oui,
(int)strnlen(ident->device_id, sizeof(ident->device_id)), ident->device_id,
ident->hw_rev >> 4, ident->hw_rev & 0xf,
ident->sw_major_rev, ident->sw_minor_rev,
desc->quirks);
}
/**
* drm_dp_read_desc - read sink/branch descriptor from DPCD
* @aux: DisplayPort AUX channel
* @desc: Device descriptor to fill from DPCD
* @is_branch: true for branch devices, false for sink devices
*
* Read DPCD 0x400 (sink) or 0x500 (branch) into @desc. Also debug log the
* identification.
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc,
bool is_branch)
{
struct drm_dp_dpcd_ident *ident = &desc->ident;
unsigned int offset = is_branch ? DP_BRANCH_OUI : DP_SINK_OUI;
int ret;
ret = drm_dp_read_ident(aux, offset, ident);
if (ret < 0)
return ret;
desc->quirks = drm_dp_get_quirks(ident, is_branch);
drm_dp_dump_desc(aux, is_branch ? "DP branch" : "DP sink", desc);
return 0;
}
EXPORT_SYMBOL(drm_dp_read_desc);
/**
* drm_dp_dump_lttpr_desc - read and dump the DPCD descriptor for an LTTPR PHY
* @aux: DisplayPort AUX channel
* @dp_phy: LTTPR PHY instance
*
* Read the DPCD LTTPR PHY descriptor for @dp_phy and print a debug message
* with its details to dmesg.
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_dump_lttpr_desc(struct drm_dp_aux *aux, enum drm_dp_phy dp_phy)
{
struct drm_dp_desc desc = {};
int ret;
if (drm_WARN_ON(aux->drm_dev, dp_phy < DP_PHY_LTTPR1 || dp_phy > DP_MAX_LTTPR_COUNT))
return -EINVAL;
ret = drm_dp_read_ident(aux, DP_OUI_PHY_REPEATER(dp_phy), &desc.ident);
if (ret < 0)
return ret;
drm_dp_dump_desc(aux, drm_dp_phy_name(dp_phy), &desc);
return 0;
}
EXPORT_SYMBOL(drm_dp_dump_lttpr_desc);
/**
* drm_dp_dsc_sink_bpp_incr() - Get bits per pixel increment
* @dsc_dpcd: DSC capabilities from DPCD
*
* Returns the bpp precision supported by the DP sink.
*/
u8 drm_dp_dsc_sink_bpp_incr(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
{
u8 bpp_increment_dpcd = dsc_dpcd[DP_DSC_BITS_PER_PIXEL_INC - DP_DSC_SUPPORT];
switch (bpp_increment_dpcd & DP_DSC_BITS_PER_PIXEL_MASK) {
case DP_DSC_BITS_PER_PIXEL_1_16:
return 16;
case DP_DSC_BITS_PER_PIXEL_1_8:
return 8;
case DP_DSC_BITS_PER_PIXEL_1_4:
return 4;
case DP_DSC_BITS_PER_PIXEL_1_2:
return 2;
case DP_DSC_BITS_PER_PIXEL_1_1:
return 1;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_dsc_sink_bpp_incr);
/**
* drm_dp_dsc_sink_max_slice_count() - Get the max slice count
* supported by the DSC sink.
* @dsc_dpcd: DSC capabilities from DPCD
* @is_edp: true if its eDP, false for DP
*
* Read the slice capabilities DPCD register from DSC sink to get
* the maximum slice count supported. This is used to populate
* the DSC parameters in the &struct drm_dsc_config by the driver.
* Driver creates an infoframe using these parameters to populate
* &struct drm_dsc_pps_infoframe. These are sent to the sink using DSC
* infoframe using the helper function drm_dsc_pps_infoframe_pack()
*
* Returns:
* Maximum slice count supported by DSC sink or 0 its invalid
*/
u8 drm_dp_dsc_sink_max_slice_count(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE],
bool is_edp)
{
u8 slice_cap1 = dsc_dpcd[DP_DSC_SLICE_CAP_1 - DP_DSC_SUPPORT];
if (is_edp) {
/* For eDP, register DSC_SLICE_CAPABILITIES_1 gives slice count */
if (slice_cap1 & DP_DSC_4_PER_DP_DSC_SINK)
return 4;
if (slice_cap1 & DP_DSC_2_PER_DP_DSC_SINK)
return 2;
if (slice_cap1 & DP_DSC_1_PER_DP_DSC_SINK)
return 1;
} else {
/* For DP, use values from DSC_SLICE_CAP_1 and DSC_SLICE_CAP2 */
u8 slice_cap2 = dsc_dpcd[DP_DSC_SLICE_CAP_2 - DP_DSC_SUPPORT];
if (slice_cap2 & DP_DSC_24_PER_DP_DSC_SINK)
return 24;
if (slice_cap2 & DP_DSC_20_PER_DP_DSC_SINK)
return 20;
if (slice_cap2 & DP_DSC_16_PER_DP_DSC_SINK)
return 16;
if (slice_cap1 & DP_DSC_12_PER_DP_DSC_SINK)
return 12;
if (slice_cap1 & DP_DSC_10_PER_DP_DSC_SINK)
return 10;
if (slice_cap1 & DP_DSC_8_PER_DP_DSC_SINK)
return 8;
if (slice_cap1 & DP_DSC_6_PER_DP_DSC_SINK)
return 6;
if (slice_cap1 & DP_DSC_4_PER_DP_DSC_SINK)
return 4;
if (slice_cap1 & DP_DSC_2_PER_DP_DSC_SINK)
return 2;
if (slice_cap1 & DP_DSC_1_PER_DP_DSC_SINK)
return 1;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_dsc_sink_max_slice_count);
/**
* drm_dp_dsc_sink_line_buf_depth() - Get the line buffer depth in bits
* @dsc_dpcd: DSC capabilities from DPCD
*
* Read the DSC DPCD register to parse the line buffer depth in bits which is
* number of bits of precision within the decoder line buffer supported by
* the DSC sink. This is used to populate the DSC parameters in the
* &struct drm_dsc_config by the driver.
* Driver creates an infoframe using these parameters to populate
* &struct drm_dsc_pps_infoframe. These are sent to the sink using DSC
* infoframe using the helper function drm_dsc_pps_infoframe_pack()
*
* Returns:
* Line buffer depth supported by DSC panel or 0 its invalid
*/
u8 drm_dp_dsc_sink_line_buf_depth(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
{
u8 line_buf_depth = dsc_dpcd[DP_DSC_LINE_BUF_BIT_DEPTH - DP_DSC_SUPPORT];
switch (line_buf_depth & DP_DSC_LINE_BUF_BIT_DEPTH_MASK) {
case DP_DSC_LINE_BUF_BIT_DEPTH_9:
return 9;
case DP_DSC_LINE_BUF_BIT_DEPTH_10:
return 10;
case DP_DSC_LINE_BUF_BIT_DEPTH_11:
return 11;
case DP_DSC_LINE_BUF_BIT_DEPTH_12:
return 12;
case DP_DSC_LINE_BUF_BIT_DEPTH_13:
return 13;
case DP_DSC_LINE_BUF_BIT_DEPTH_14:
return 14;
case DP_DSC_LINE_BUF_BIT_DEPTH_15:
return 15;
case DP_DSC_LINE_BUF_BIT_DEPTH_16:
return 16;
case DP_DSC_LINE_BUF_BIT_DEPTH_8:
return 8;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_dsc_sink_line_buf_depth);
/**
* drm_dp_dsc_sink_supported_input_bpcs() - Get all the input bits per component
* values supported by the DSC sink.
* @dsc_dpcd: DSC capabilities from DPCD
* @dsc_bpc: An array to be filled by this helper with supported
* input bpcs.
*
* Read the DSC DPCD from the sink device to parse the supported bits per
* component values. This is used to populate the DSC parameters
* in the &struct drm_dsc_config by the driver.
* Driver creates an infoframe using these parameters to populate
* &struct drm_dsc_pps_infoframe. These are sent to the sink using DSC
* infoframe using the helper function drm_dsc_pps_infoframe_pack()
*
* Returns:
* Number of input BPC values parsed from the DPCD
*/
int drm_dp_dsc_sink_supported_input_bpcs(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE],
u8 dsc_bpc[3])
{
int num_bpc = 0;
u8 color_depth = dsc_dpcd[DP_DSC_DEC_COLOR_DEPTH_CAP - DP_DSC_SUPPORT];
if (!drm_dp_sink_supports_dsc(dsc_dpcd))
return 0;
if (color_depth & DP_DSC_12_BPC)
dsc_bpc[num_bpc++] = 12;
if (color_depth & DP_DSC_10_BPC)
dsc_bpc[num_bpc++] = 10;
/* A DP DSC Sink device shall support 8 bpc. */
dsc_bpc[num_bpc++] = 8;
return num_bpc;
}
EXPORT_SYMBOL(drm_dp_dsc_sink_supported_input_bpcs);
static int drm_dp_read_lttpr_regs(struct drm_dp_aux *aux,
const u8 dpcd[DP_RECEIVER_CAP_SIZE], int address,
u8 *buf, int buf_size)
{
/*
* At least the DELL P2715Q monitor with a DPCD_REV < 0x14 returns
* corrupted values when reading from the 0xF0000- range with a block
* size bigger than 1.
*/
int block_size = dpcd[DP_DPCD_REV] < 0x14 ? 1 : buf_size;
int offset;
int ret;
for (offset = 0; offset < buf_size; offset += block_size) {
ret = drm_dp_dpcd_read_data(aux,
address + offset,
&buf[offset], block_size);
if (ret < 0)
return ret;
}
return 0;
}
/**
* drm_dp_read_lttpr_common_caps - read the LTTPR common capabilities
* @aux: DisplayPort AUX channel
* @dpcd: DisplayPort configuration data
* @caps: buffer to return the capability info in
*
* Read capabilities common to all LTTPRs.
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_read_lttpr_common_caps(struct drm_dp_aux *aux,
const u8 dpcd[DP_RECEIVER_CAP_SIZE],
u8 caps[DP_LTTPR_COMMON_CAP_SIZE])
{
return drm_dp_read_lttpr_regs(aux, dpcd,
DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV,
caps, DP_LTTPR_COMMON_CAP_SIZE);
}
EXPORT_SYMBOL(drm_dp_read_lttpr_common_caps);
/**
* drm_dp_read_lttpr_phy_caps - read the capabilities for a given LTTPR PHY
* @aux: DisplayPort AUX channel
* @dpcd: DisplayPort configuration data
* @dp_phy: LTTPR PHY to read the capabilities for
* @caps: buffer to return the capability info in
*
* Read the capabilities for the given LTTPR PHY.
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_read_lttpr_phy_caps(struct drm_dp_aux *aux,
const u8 dpcd[DP_RECEIVER_CAP_SIZE],
enum drm_dp_phy dp_phy,
u8 caps[DP_LTTPR_PHY_CAP_SIZE])
{
return drm_dp_read_lttpr_regs(aux, dpcd,
DP_TRAINING_AUX_RD_INTERVAL_PHY_REPEATER(dp_phy),
caps, DP_LTTPR_PHY_CAP_SIZE);
}
EXPORT_SYMBOL(drm_dp_read_lttpr_phy_caps);
static u8 dp_lttpr_common_cap(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE], int r)
{
return caps[r - DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV];
}
/**
* drm_dp_lttpr_count - get the number of detected LTTPRs
* @caps: LTTPR common capabilities
*
* Get the number of detected LTTPRs from the LTTPR common capabilities info.
*
* Returns:
* -ERANGE if more than supported number (8) of LTTPRs are detected
* -EINVAL if the DP_PHY_REPEATER_CNT register contains an invalid value
* otherwise the number of detected LTTPRs
*/
int drm_dp_lttpr_count(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE])
{
u8 count = dp_lttpr_common_cap(caps, DP_PHY_REPEATER_CNT);
switch (hweight8(count)) {
case 0:
return 0;
case 1:
return 8 - ilog2(count);
case 8:
return -ERANGE;
default:
return -EINVAL;
}
}
EXPORT_SYMBOL(drm_dp_lttpr_count);
/**
* drm_dp_lttpr_max_link_rate - get the maximum link rate supported by all LTTPRs
* @caps: LTTPR common capabilities
*
* Returns the maximum link rate supported by all detected LTTPRs.
*/
int drm_dp_lttpr_max_link_rate(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE])
{
u8 rate = dp_lttpr_common_cap(caps, DP_MAX_LINK_RATE_PHY_REPEATER);
return drm_dp_bw_code_to_link_rate(rate);
}
EXPORT_SYMBOL(drm_dp_lttpr_max_link_rate);
/**
* drm_dp_lttpr_set_transparent_mode() - set the LTTPR in transparent mode
* @aux: DisplayPort AUX channel
* @enable: Enable or disable transparent mode
*
* Returns: 0 on success or a negative error code on failure.
*/
int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux, bool enable)
{
u8 val = enable ? DP_PHY_REPEATER_MODE_TRANSPARENT :
DP_PHY_REPEATER_MODE_NON_TRANSPARENT;
int ret = drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_MODE, val);
if (ret < 0)
return ret;
return (ret == 1) ? 0 : -EIO;
}
EXPORT_SYMBOL(drm_dp_lttpr_set_transparent_mode);
/**
* drm_dp_lttpr_init() - init LTTPR transparency mode according to DP standard
* @aux: DisplayPort AUX channel
* @lttpr_count: Number of LTTPRs. Between 0 and 8, according to DP standard.
* Negative error code for any non-valid number.
* See drm_dp_lttpr_count().
*
* Returns: 0 on success or a negative error code on failure.
*/
int drm_dp_lttpr_init(struct drm_dp_aux *aux, int lttpr_count)
{
int ret;
if (!lttpr_count)
return 0;
/*
* See DP Standard v2.0 3.6.6.1 about the explicit disabling of
* non-transparent mode and the disable->enable non-transparent mode
* sequence.
*/
ret = drm_dp_lttpr_set_transparent_mode(aux, true);
if (ret)
return ret;
if (lttpr_count < 0)
return -ENODEV;
if (drm_dp_lttpr_set_transparent_mode(aux, false)) {
/*
* Roll-back to transparent mode if setting non-transparent
* mode has failed
*/
drm_dp_lttpr_set_transparent_mode(aux, true);
return -EINVAL;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_lttpr_init);
/**
* drm_dp_lttpr_max_lane_count - get the maximum lane count supported by all LTTPRs
* @caps: LTTPR common capabilities
*
* Returns the maximum lane count supported by all detected LTTPRs.
*/
int drm_dp_lttpr_max_lane_count(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE])
{
u8 max_lanes = dp_lttpr_common_cap(caps, DP_MAX_LANE_COUNT_PHY_REPEATER);
return max_lanes & DP_MAX_LANE_COUNT_MASK;
}
EXPORT_SYMBOL(drm_dp_lttpr_max_lane_count);
/**
* drm_dp_lttpr_voltage_swing_level_3_supported - check for LTTPR vswing3 support
* @caps: LTTPR PHY capabilities
*
* Returns true if the @caps for an LTTPR TX PHY indicate support for
* voltage swing level 3.
*/
bool
drm_dp_lttpr_voltage_swing_level_3_supported(const u8 caps[DP_LTTPR_PHY_CAP_SIZE])
{
u8 txcap = dp_lttpr_phy_cap(caps, DP_TRANSMITTER_CAPABILITY_PHY_REPEATER1);
return txcap & DP_VOLTAGE_SWING_LEVEL_3_SUPPORTED;
}
EXPORT_SYMBOL(drm_dp_lttpr_voltage_swing_level_3_supported);
/**
* drm_dp_lttpr_pre_emphasis_level_3_supported - check for LTTPR preemph3 support
* @caps: LTTPR PHY capabilities
*
* Returns true if the @caps for an LTTPR TX PHY indicate support for
* pre-emphasis level 3.
*/
bool
drm_dp_lttpr_pre_emphasis_level_3_supported(const u8 caps[DP_LTTPR_PHY_CAP_SIZE])
{
u8 txcap = dp_lttpr_phy_cap(caps, DP_TRANSMITTER_CAPABILITY_PHY_REPEATER1);
return txcap & DP_PRE_EMPHASIS_LEVEL_3_SUPPORTED;
}
EXPORT_SYMBOL(drm_dp_lttpr_pre_emphasis_level_3_supported);
/**
* drm_dp_get_phy_test_pattern() - get the requested pattern from the sink.
* @aux: DisplayPort AUX channel
* @data: DP phy compliance test parameters.
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_get_phy_test_pattern(struct drm_dp_aux *aux,
struct drm_dp_phy_test_params *data)
{
int err;
u8 rate, lanes;
err = drm_dp_dpcd_read_byte(aux, DP_TEST_LINK_RATE, &rate);
if (err < 0)
return err;
data->link_rate = drm_dp_bw_code_to_link_rate(rate);
err = drm_dp_dpcd_read_byte(aux, DP_TEST_LANE_COUNT, &lanes);
if (err < 0)
return err;
data->num_lanes = lanes & DP_MAX_LANE_COUNT_MASK;
if (lanes & DP_ENHANCED_FRAME_CAP)
data->enhanced_frame_cap = true;
err = drm_dp_dpcd_read_byte(aux, DP_PHY_TEST_PATTERN, &data->phy_pattern);
if (err < 0)
return err;
switch (data->phy_pattern) {
case DP_PHY_TEST_PATTERN_80BIT_CUSTOM:
err = drm_dp_dpcd_read_data(aux, DP_TEST_80BIT_CUSTOM_PATTERN_7_0,
&data->custom80, sizeof(data->custom80));
if (err < 0)
return err;
break;
case DP_PHY_TEST_PATTERN_CP2520:
err = drm_dp_dpcd_read_data(aux, DP_TEST_HBR2_SCRAMBLER_RESET,
&data->hbr2_reset,
sizeof(data->hbr2_reset));
if (err < 0)
return err;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_get_phy_test_pattern);
/**
* drm_dp_set_phy_test_pattern() - set the pattern to the sink.
* @aux: DisplayPort AUX channel
* @data: DP phy compliance test parameters.
* @dp_rev: DP revision to use for compliance testing
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_set_phy_test_pattern(struct drm_dp_aux *aux,
struct drm_dp_phy_test_params *data, u8 dp_rev)
{
int err, i;
u8 test_pattern;
test_pattern = data->phy_pattern;
if (dp_rev < 0x12) {
test_pattern = (test_pattern << 2) &
DP_LINK_QUAL_PATTERN_11_MASK;
err = drm_dp_dpcd_write_byte(aux, DP_TRAINING_PATTERN_SET,
test_pattern);
if (err < 0)
return err;
} else {
for (i = 0; i < data->num_lanes; i++) {
err = drm_dp_dpcd_write_byte(aux,
DP_LINK_QUAL_LANE0_SET + i,
test_pattern);
if (err < 0)
return err;
}
}
return 0;
}
EXPORT_SYMBOL(drm_dp_set_phy_test_pattern);
static const char *dp_pixelformat_get_name(enum dp_pixelformat pixelformat)
{
if (pixelformat < 0 || pixelformat > DP_PIXELFORMAT_RESERVED)
return "Invalid";
switch (pixelformat) {
case DP_PIXELFORMAT_RGB:
return "RGB";
case DP_PIXELFORMAT_YUV444:
return "YUV444";
case DP_PIXELFORMAT_YUV422:
return "YUV422";
case DP_PIXELFORMAT_YUV420:
return "YUV420";
case DP_PIXELFORMAT_Y_ONLY:
return "Y_ONLY";
case DP_PIXELFORMAT_RAW:
return "RAW";
default:
return "Reserved";
}
}
static const char *dp_colorimetry_get_name(enum dp_pixelformat pixelformat,
enum dp_colorimetry colorimetry)
{
if (pixelformat < 0 || pixelformat > DP_PIXELFORMAT_RESERVED)
return "Invalid";
switch (colorimetry) {
case DP_COLORIMETRY_DEFAULT:
switch (pixelformat) {
case DP_PIXELFORMAT_RGB:
return "sRGB";
case DP_PIXELFORMAT_YUV444:
case DP_PIXELFORMAT_YUV422:
case DP_PIXELFORMAT_YUV420:
return "BT.601";
case DP_PIXELFORMAT_Y_ONLY:
return "DICOM PS3.14";
case DP_PIXELFORMAT_RAW:
return "Custom Color Profile";
default:
return "Reserved";
}
case DP_COLORIMETRY_RGB_WIDE_FIXED: /* and DP_COLORIMETRY_BT709_YCC */
switch (pixelformat) {
case DP_PIXELFORMAT_RGB:
return "Wide Fixed";
case DP_PIXELFORMAT_YUV444:
case DP_PIXELFORMAT_YUV422:
case DP_PIXELFORMAT_YUV420:
return "BT.709";
default:
return "Reserved";
}
case DP_COLORIMETRY_RGB_WIDE_FLOAT: /* and DP_COLORIMETRY_XVYCC_601 */
switch (pixelformat) {
case DP_PIXELFORMAT_RGB:
return "Wide Float";
case DP_PIXELFORMAT_YUV444:
case DP_PIXELFORMAT_YUV422:
case DP_PIXELFORMAT_YUV420:
return "xvYCC 601";
default:
return "Reserved";
}
case DP_COLORIMETRY_OPRGB: /* and DP_COLORIMETRY_XVYCC_709 */
switch (pixelformat) {
case DP_PIXELFORMAT_RGB:
return "OpRGB";
case DP_PIXELFORMAT_YUV444:
case DP_PIXELFORMAT_YUV422:
case DP_PIXELFORMAT_YUV420:
return "xvYCC 709";
default:
return "Reserved";
}
case DP_COLORIMETRY_DCI_P3_RGB: /* and DP_COLORIMETRY_SYCC_601 */
switch (pixelformat) {
case DP_PIXELFORMAT_RGB:
return "DCI-P3";
case DP_PIXELFORMAT_YUV444:
case DP_PIXELFORMAT_YUV422:
case DP_PIXELFORMAT_YUV420:
return "sYCC 601";
default:
return "Reserved";
}
case DP_COLORIMETRY_RGB_CUSTOM: /* and DP_COLORIMETRY_OPYCC_601 */
switch (pixelformat) {
case DP_PIXELFORMAT_RGB:
return "Custom Profile";
case DP_PIXELFORMAT_YUV444:
case DP_PIXELFORMAT_YUV422:
case DP_PIXELFORMAT_YUV420:
return "OpYCC 601";
default:
return "Reserved";
}
case DP_COLORIMETRY_BT2020_RGB: /* and DP_COLORIMETRY_BT2020_CYCC */
switch (pixelformat) {
case DP_PIXELFORMAT_RGB:
return "BT.2020 RGB";
case DP_PIXELFORMAT_YUV444:
case DP_PIXELFORMAT_YUV422:
case DP_PIXELFORMAT_YUV420:
return "BT.2020 CYCC";
default:
return "Reserved";
}
case DP_COLORIMETRY_BT2020_YCC:
switch (pixelformat) {
case DP_PIXELFORMAT_YUV444:
case DP_PIXELFORMAT_YUV422:
case DP_PIXELFORMAT_YUV420:
return "BT.2020 YCC";
default:
return "Reserved";
}
default:
return "Invalid";
}
}
static const char *dp_dynamic_range_get_name(enum dp_dynamic_range dynamic_range)
{
switch (dynamic_range) {
case DP_DYNAMIC_RANGE_VESA:
return "VESA range";
case DP_DYNAMIC_RANGE_CTA:
return "CTA range";
default:
return "Invalid";
}
}
static const char *dp_content_type_get_name(enum dp_content_type content_type)
{
switch (content_type) {
case DP_CONTENT_TYPE_NOT_DEFINED:
return "Not defined";
case DP_CONTENT_TYPE_GRAPHICS:
return "Graphics";
case DP_CONTENT_TYPE_PHOTO:
return "Photo";
case DP_CONTENT_TYPE_VIDEO:
return "Video";
case DP_CONTENT_TYPE_GAME:
return "Game";
default:
return "Reserved";
}
}
void drm_dp_vsc_sdp_log(struct drm_printer *p, const struct drm_dp_vsc_sdp *vsc)
{
drm_printf(p, "DP SDP: VSC, revision %u, length %u\n",
vsc->revision, vsc->length);
drm_printf(p, " pixelformat: %s\n",
dp_pixelformat_get_name(vsc->pixelformat));
drm_printf(p, " colorimetry: %s\n",
dp_colorimetry_get_name(vsc->pixelformat, vsc->colorimetry));
drm_printf(p, " bpc: %u\n", vsc->bpc);
drm_printf(p, " dynamic range: %s\n",
dp_dynamic_range_get_name(vsc->dynamic_range));
drm_printf(p, " content type: %s\n",
dp_content_type_get_name(vsc->content_type));
}
EXPORT_SYMBOL(drm_dp_vsc_sdp_log);
void drm_dp_as_sdp_log(struct drm_printer *p, const struct drm_dp_as_sdp *as_sdp)
{
drm_printf(p, "DP SDP: AS_SDP, revision %u, length %u\n",
as_sdp->revision, as_sdp->length);
drm_printf(p, " vtotal: %d\n", as_sdp->vtotal);
drm_printf(p, " target_rr: %d\n", as_sdp->target_rr);
drm_printf(p, " duration_incr_ms: %d\n", as_sdp->duration_incr_ms);
drm_printf(p, " duration_decr_ms: %d\n", as_sdp->duration_decr_ms);
drm_printf(p, " operation_mode: %d\n", as_sdp->mode);
}
EXPORT_SYMBOL(drm_dp_as_sdp_log);
/**
* drm_dp_as_sdp_supported() - check if adaptive sync sdp is supported
* @aux: DisplayPort AUX channel
* @dpcd: DisplayPort configuration data
*
* Returns true if adaptive sync sdp is supported, else returns false
*/
bool drm_dp_as_sdp_supported(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE])
{
u8 rx_feature;
if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_13)
return false;
if (drm_dp_dpcd_read_byte(aux, DP_DPRX_FEATURE_ENUMERATION_LIST_CONT_1,
&rx_feature) < 0) {
drm_dbg_dp(aux->drm_dev,
"Failed to read DP_DPRX_FEATURE_ENUMERATION_LIST_CONT_1\n");
return false;
}
return (rx_feature & DP_ADAPTIVE_SYNC_SDP_SUPPORTED);
}
EXPORT_SYMBOL(drm_dp_as_sdp_supported);
/**
* drm_dp_vsc_sdp_supported() - check if vsc sdp is supported
* @aux: DisplayPort AUX channel
* @dpcd: DisplayPort configuration data
*
* Returns true if vsc sdp is supported, else returns false
*/
bool drm_dp_vsc_sdp_supported(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE])
{
u8 rx_feature;
if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_13)
return false;
if (drm_dp_dpcd_read_byte(aux, DP_DPRX_FEATURE_ENUMERATION_LIST, &rx_feature) < 0) {
drm_dbg_dp(aux->drm_dev, "failed to read DP_DPRX_FEATURE_ENUMERATION_LIST\n");
return false;
}
return (rx_feature & DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED);
}
EXPORT_SYMBOL(drm_dp_vsc_sdp_supported);
/**
* drm_dp_vsc_sdp_pack() - pack a given vsc sdp into generic dp_sdp
* @vsc: vsc sdp initialized according to its purpose as defined in
* table 2-118 - table 2-120 in DP 1.4a specification
* @sdp: valid handle to the generic dp_sdp which will be packed
*
* Returns length of sdp on success and error code on failure
*/
ssize_t drm_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc,
struct dp_sdp *sdp)
{
size_t length = sizeof(struct dp_sdp);
memset(sdp, 0, sizeof(struct dp_sdp));
/*
* Prepare VSC Header for SU as per DP 1.4a spec, Table 2-119
* VSC SDP Header Bytes
*/
sdp->sdp_header.HB0 = 0; /* Secondary-Data Packet ID = 0 */
sdp->sdp_header.HB1 = vsc->sdp_type; /* Secondary-data Packet Type */
sdp->sdp_header.HB2 = vsc->revision; /* Revision Number */
sdp->sdp_header.HB3 = vsc->length; /* Number of Valid Data Bytes */
if (vsc->revision == 0x6) {
sdp->db[0] = 1;
sdp->db[3] = 1;
}
/*
* Revision 0x5 and revision 0x7 supports Pixel Encoding/Colorimetry
* Format as per DP 1.4a spec and DP 2.0 respectively.
*/
if (!(vsc->revision == 0x5 || vsc->revision == 0x7))
goto out;
/* VSC SDP Payload for DB16 through DB18 */
/* Pixel Encoding and Colorimetry Formats */
sdp->db[16] = (vsc->pixelformat & 0xf) << 4; /* DB16[7:4] */
sdp->db[16] |= vsc->colorimetry & 0xf; /* DB16[3:0] */
switch (vsc->bpc) {
case 6:
/* 6bpc: 0x0 */
break;
case 8:
sdp->db[17] = 0x1; /* DB17[3:0] */
break;
case 10:
sdp->db[17] = 0x2;
break;
case 12:
sdp->db[17] = 0x3;
break;
case 16:
sdp->db[17] = 0x4;
break;
default:
WARN(1, "Missing case %d\n", vsc->bpc);
return -EINVAL;
}
/* Dynamic Range and Component Bit Depth */
if (vsc->dynamic_range == DP_DYNAMIC_RANGE_CTA)
sdp->db[17] |= 0x80; /* DB17[7] */
/* Content Type */
sdp->db[18] = vsc->content_type & 0x7;
out:
return length;
}
EXPORT_SYMBOL(drm_dp_vsc_sdp_pack);
/**
* drm_dp_get_pcon_max_frl_bw() - maximum frl supported by PCON
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
*
* Returns maximum frl bandwidth supported by PCON in GBPS,
* returns 0 if not supported.
*/
int drm_dp_get_pcon_max_frl_bw(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4])
{
int bw;
u8 buf;
buf = port_cap[2];
bw = buf & DP_PCON_MAX_FRL_BW;
switch (bw) {
case DP_PCON_MAX_9GBPS:
return 9;
case DP_PCON_MAX_18GBPS:
return 18;
case DP_PCON_MAX_24GBPS:
return 24;
case DP_PCON_MAX_32GBPS:
return 32;
case DP_PCON_MAX_40GBPS:
return 40;
case DP_PCON_MAX_48GBPS:
return 48;
case DP_PCON_MAX_0GBPS:
default:
return 0;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_get_pcon_max_frl_bw);
/**
* drm_dp_pcon_frl_prepare() - Prepare PCON for FRL.
* @aux: DisplayPort AUX channel
* @enable_frl_ready_hpd: Configure DP_PCON_ENABLE_HPD_READY.
*
* Returns 0 if success, else returns negative error code.
*/
int drm_dp_pcon_frl_prepare(struct drm_dp_aux *aux, bool enable_frl_ready_hpd)
{
u8 buf = DP_PCON_ENABLE_SOURCE_CTL_MODE |
DP_PCON_ENABLE_LINK_FRL_MODE;
if (enable_frl_ready_hpd)
buf |= DP_PCON_ENABLE_HPD_READY;
return drm_dp_dpcd_write_byte(aux, DP_PCON_HDMI_LINK_CONFIG_1, buf);
}
EXPORT_SYMBOL(drm_dp_pcon_frl_prepare);
/**
* drm_dp_pcon_is_frl_ready() - Is PCON ready for FRL
* @aux: DisplayPort AUX channel
*
* Returns true if success, else returns false.
*/
bool drm_dp_pcon_is_frl_ready(struct drm_dp_aux *aux)
{
int ret;
u8 buf;
ret = drm_dp_dpcd_read_byte(aux, DP_PCON_HDMI_TX_LINK_STATUS, &buf);
if (ret < 0)
return false;
if (buf & DP_PCON_FRL_READY)
return true;
return false;
}
EXPORT_SYMBOL(drm_dp_pcon_is_frl_ready);
/**
* drm_dp_pcon_frl_configure_1() - Set HDMI LINK Configuration-Step1
* @aux: DisplayPort AUX channel
* @max_frl_gbps: maximum frl bw to be configured between PCON and HDMI sink
* @frl_mode: FRL Training mode, it can be either Concurrent or Sequential.
* In Concurrent Mode, the FRL link bring up can be done along with
* DP Link training. In Sequential mode, the FRL link bring up is done prior to
* the DP Link training.
*
* Returns 0 if success, else returns negative error code.
*/
int drm_dp_pcon_frl_configure_1(struct drm_dp_aux *aux, int max_frl_gbps,
u8 frl_mode)
{
int ret;
u8 buf;
ret = drm_dp_dpcd_read_byte(aux, DP_PCON_HDMI_LINK_CONFIG_1, &buf);
if (ret < 0)
return ret;
if (frl_mode == DP_PCON_ENABLE_CONCURRENT_LINK)
buf |= DP_PCON_ENABLE_CONCURRENT_LINK;
else
buf &= ~DP_PCON_ENABLE_CONCURRENT_LINK;
switch (max_frl_gbps) {
case 9:
buf |= DP_PCON_ENABLE_MAX_BW_9GBPS;
break;
case 18:
buf |= DP_PCON_ENABLE_MAX_BW_18GBPS;
break;
case 24:
buf |= DP_PCON_ENABLE_MAX_BW_24GBPS;
break;
case 32:
buf |= DP_PCON_ENABLE_MAX_BW_32GBPS;
break;
case 40:
buf |= DP_PCON_ENABLE_MAX_BW_40GBPS;
break;
case 48:
buf |= DP_PCON_ENABLE_MAX_BW_48GBPS;
break;
case 0:
buf |= DP_PCON_ENABLE_MAX_BW_0GBPS;
break;
default:
return -EINVAL;
}
return drm_dp_dpcd_write_byte(aux, DP_PCON_HDMI_LINK_CONFIG_1, buf);
}
EXPORT_SYMBOL(drm_dp_pcon_frl_configure_1);
/**
* drm_dp_pcon_frl_configure_2() - Set HDMI Link configuration Step-2
* @aux: DisplayPort AUX channel
* @max_frl_mask : Max FRL BW to be tried by the PCON with HDMI Sink
* @frl_type : FRL training type, can be Extended, or Normal.
* In Normal FRL training, the PCON tries each frl bw from the max_frl_mask
* starting from min, and stops when link training is successful. In Extended
* FRL training, all frl bw selected in the mask are trained by the PCON.
*
* Returns 0 if success, else returns negative error code.
*/
int drm_dp_pcon_frl_configure_2(struct drm_dp_aux *aux, int max_frl_mask,
u8 frl_type)
{
int ret;
u8 buf = max_frl_mask;
if (frl_type == DP_PCON_FRL_LINK_TRAIN_EXTENDED)
buf |= DP_PCON_FRL_LINK_TRAIN_EXTENDED;
else
buf &= ~DP_PCON_FRL_LINK_TRAIN_EXTENDED;
return drm_dp_dpcd_write_byte(aux, DP_PCON_HDMI_LINK_CONFIG_2, buf);
if (ret < 0)
return ret;
return 0;
}
EXPORT_SYMBOL(drm_dp_pcon_frl_configure_2);
/**
* drm_dp_pcon_reset_frl_config() - Re-Set HDMI Link configuration.
* @aux: DisplayPort AUX channel
*
* Returns 0 if success, else returns negative error code.
*/
int drm_dp_pcon_reset_frl_config(struct drm_dp_aux *aux)
{
return drm_dp_dpcd_write_byte(aux, DP_PCON_HDMI_LINK_CONFIG_1, 0x0);
}
EXPORT_SYMBOL(drm_dp_pcon_reset_frl_config);
/**
* drm_dp_pcon_frl_enable() - Enable HDMI link through FRL
* @aux: DisplayPort AUX channel
*
* Returns 0 if success, else returns negative error code.
*/
int drm_dp_pcon_frl_enable(struct drm_dp_aux *aux)
{
int ret;
u8 buf = 0;
ret = drm_dp_dpcd_read_byte(aux, DP_PCON_HDMI_LINK_CONFIG_1, &buf);
if (ret < 0)
return ret;
if (!(buf & DP_PCON_ENABLE_SOURCE_CTL_MODE)) {
drm_dbg_kms(aux->drm_dev, "%s: PCON in Autonomous mode, can't enable FRL\n",
aux->name);
return -EINVAL;
}
buf |= DP_PCON_ENABLE_HDMI_LINK;
return drm_dp_dpcd_write_byte(aux, DP_PCON_HDMI_LINK_CONFIG_1, buf);
}
EXPORT_SYMBOL(drm_dp_pcon_frl_enable);
/**
* drm_dp_pcon_hdmi_link_active() - check if the PCON HDMI LINK status is active.
* @aux: DisplayPort AUX channel
*
* Returns true if link is active else returns false.
*/
bool drm_dp_pcon_hdmi_link_active(struct drm_dp_aux *aux)
{
u8 buf;
int ret;
ret = drm_dp_dpcd_read_byte(aux, DP_PCON_HDMI_TX_LINK_STATUS, &buf);
if (ret < 0)
return false;
return buf & DP_PCON_HDMI_TX_LINK_ACTIVE;
}
EXPORT_SYMBOL(drm_dp_pcon_hdmi_link_active);
/**
* drm_dp_pcon_hdmi_link_mode() - get the PCON HDMI LINK MODE
* @aux: DisplayPort AUX channel
* @frl_trained_mask: pointer to store bitmask of the trained bw configuration.
* Valid only if the MODE returned is FRL. For Normal Link training mode
* only 1 of the bits will be set, but in case of Extended mode, more than
* one bits can be set.
*
* Returns the link mode : TMDS or FRL on success, else returns negative error
* code.
*/
int drm_dp_pcon_hdmi_link_mode(struct drm_dp_aux *aux, u8 *frl_trained_mask)
{
u8 buf;
int mode;
int ret;
ret = drm_dp_dpcd_read_byte(aux, DP_PCON_HDMI_POST_FRL_STATUS, &buf);
if (ret < 0)
return ret;
mode = buf & DP_PCON_HDMI_LINK_MODE;
if (frl_trained_mask && DP_PCON_HDMI_MODE_FRL == mode)
*frl_trained_mask = (buf & DP_PCON_HDMI_FRL_TRAINED_BW) >> 1;
return mode;
}
EXPORT_SYMBOL(drm_dp_pcon_hdmi_link_mode);
/**
* drm_dp_pcon_hdmi_frl_link_error_count() - print the error count per lane
* during link failure between PCON and HDMI sink
* @aux: DisplayPort AUX channel
* @connector: DRM connector
* code.
**/
void drm_dp_pcon_hdmi_frl_link_error_count(struct drm_dp_aux *aux,
struct drm_connector *connector)
{
u8 buf, error_count;
int i, num_error;
struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
for (i = 0; i < hdmi->max_lanes; i++) {
if (drm_dp_dpcd_read_byte(aux, DP_PCON_HDMI_ERROR_STATUS_LN0 + i, &buf) < 0)
return;
error_count = buf & DP_PCON_HDMI_ERROR_COUNT_MASK;
switch (error_count) {
case DP_PCON_HDMI_ERROR_COUNT_HUNDRED_PLUS:
num_error = 100;
break;
case DP_PCON_HDMI_ERROR_COUNT_TEN_PLUS:
num_error = 10;
break;
case DP_PCON_HDMI_ERROR_COUNT_THREE_PLUS:
num_error = 3;
break;
default:
num_error = 0;
}
drm_err(aux->drm_dev, "%s: More than %d errors since the last read for lane %d",
aux->name, num_error, i);
}
}
EXPORT_SYMBOL(drm_dp_pcon_hdmi_frl_link_error_count);
/*
* drm_dp_pcon_enc_is_dsc_1_2 - Does PCON Encoder supports DSC 1.2
* @pcon_dsc_dpcd: DSC capabilities of the PCON DSC Encoder
*
* Returns true is PCON encoder is DSC 1.2 else returns false.
*/
bool drm_dp_pcon_enc_is_dsc_1_2(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE])
{
u8 buf;
u8 major_v, minor_v;
buf = pcon_dsc_dpcd[DP_PCON_DSC_VERSION - DP_PCON_DSC_ENCODER];
major_v = (buf & DP_PCON_DSC_MAJOR_MASK) >> DP_PCON_DSC_MAJOR_SHIFT;
minor_v = (buf & DP_PCON_DSC_MINOR_MASK) >> DP_PCON_DSC_MINOR_SHIFT;
if (major_v == 1 && minor_v == 2)
return true;
return false;
}
EXPORT_SYMBOL(drm_dp_pcon_enc_is_dsc_1_2);
/*
* drm_dp_pcon_dsc_max_slices - Get max slices supported by PCON DSC Encoder
* @pcon_dsc_dpcd: DSC capabilities of the PCON DSC Encoder
*
* Returns maximum no. of slices supported by the PCON DSC Encoder.
*/
int drm_dp_pcon_dsc_max_slices(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE])
{
u8 slice_cap1, slice_cap2;
slice_cap1 = pcon_dsc_dpcd[DP_PCON_DSC_SLICE_CAP_1 - DP_PCON_DSC_ENCODER];
slice_cap2 = pcon_dsc_dpcd[DP_PCON_DSC_SLICE_CAP_2 - DP_PCON_DSC_ENCODER];
if (slice_cap2 & DP_PCON_DSC_24_PER_DSC_ENC)
return 24;
if (slice_cap2 & DP_PCON_DSC_20_PER_DSC_ENC)
return 20;
if (slice_cap2 & DP_PCON_DSC_16_PER_DSC_ENC)
return 16;
if (slice_cap1 & DP_PCON_DSC_12_PER_DSC_ENC)
return 12;
if (slice_cap1 & DP_PCON_DSC_10_PER_DSC_ENC)
return 10;
if (slice_cap1 & DP_PCON_DSC_8_PER_DSC_ENC)
return 8;
if (slice_cap1 & DP_PCON_DSC_6_PER_DSC_ENC)
return 6;
if (slice_cap1 & DP_PCON_DSC_4_PER_DSC_ENC)
return 4;
if (slice_cap1 & DP_PCON_DSC_2_PER_DSC_ENC)
return 2;
if (slice_cap1 & DP_PCON_DSC_1_PER_DSC_ENC)
return 1;
return 0;
}
EXPORT_SYMBOL(drm_dp_pcon_dsc_max_slices);
/*
* drm_dp_pcon_dsc_max_slice_width() - Get max slice width for Pcon DSC encoder
* @pcon_dsc_dpcd: DSC capabilities of the PCON DSC Encoder
*
* Returns maximum width of the slices in pixel width i.e. no. of pixels x 320.
*/
int drm_dp_pcon_dsc_max_slice_width(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE])
{
u8 buf;
buf = pcon_dsc_dpcd[DP_PCON_DSC_MAX_SLICE_WIDTH - DP_PCON_DSC_ENCODER];
return buf * DP_DSC_SLICE_WIDTH_MULTIPLIER;
}
EXPORT_SYMBOL(drm_dp_pcon_dsc_max_slice_width);
/*
* drm_dp_pcon_dsc_bpp_incr() - Get bits per pixel increment for PCON DSC encoder
* @pcon_dsc_dpcd: DSC capabilities of the PCON DSC Encoder
*
* Returns the bpp precision supported by the PCON encoder.
*/
int drm_dp_pcon_dsc_bpp_incr(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE])
{
u8 buf;
buf = pcon_dsc_dpcd[DP_PCON_DSC_BPP_INCR - DP_PCON_DSC_ENCODER];
switch (buf & DP_PCON_DSC_BPP_INCR_MASK) {
case DP_PCON_DSC_ONE_16TH_BPP:
return 16;
case DP_PCON_DSC_ONE_8TH_BPP:
return 8;
case DP_PCON_DSC_ONE_4TH_BPP:
return 4;
case DP_PCON_DSC_ONE_HALF_BPP:
return 2;
case DP_PCON_DSC_ONE_BPP:
return 1;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_pcon_dsc_bpp_incr);
static
int drm_dp_pcon_configure_dsc_enc(struct drm_dp_aux *aux, u8 pps_buf_config)
{
u8 buf;
int ret;
ret = drm_dp_dpcd_read_byte(aux, DP_PROTOCOL_CONVERTER_CONTROL_2, &buf);
if (ret < 0)
return ret;
buf |= DP_PCON_ENABLE_DSC_ENCODER;
if (pps_buf_config <= DP_PCON_ENC_PPS_OVERRIDE_EN_BUFFER) {
buf &= ~DP_PCON_ENCODER_PPS_OVERRIDE_MASK;
buf |= pps_buf_config << 2;
}
return drm_dp_dpcd_write_byte(aux, DP_PROTOCOL_CONVERTER_CONTROL_2, buf);
}
/**
* drm_dp_pcon_pps_default() - Let PCON fill the default pps parameters
* for DSC1.2 between PCON & HDMI2.1 sink
* @aux: DisplayPort AUX channel
*
* Returns 0 on success, else returns negative error code.
*/
int drm_dp_pcon_pps_default(struct drm_dp_aux *aux)
{
return drm_dp_pcon_configure_dsc_enc(aux, DP_PCON_ENC_PPS_OVERRIDE_DISABLED);
}
EXPORT_SYMBOL(drm_dp_pcon_pps_default);
/**
* drm_dp_pcon_pps_override_buf() - Configure PPS encoder override buffer for
* HDMI sink
* @aux: DisplayPort AUX channel
* @pps_buf: 128 bytes to be written into PPS buffer for HDMI sink by PCON.
*
* Returns 0 on success, else returns negative error code.
*/
int drm_dp_pcon_pps_override_buf(struct drm_dp_aux *aux, u8 pps_buf[128])
{
int ret;
ret = drm_dp_dpcd_write_data(aux, DP_PCON_HDMI_PPS_OVERRIDE_BASE, &pps_buf, 128);
if (ret < 0)
return ret;
return drm_dp_pcon_configure_dsc_enc(aux, DP_PCON_ENC_PPS_OVERRIDE_EN_BUFFER);
}
EXPORT_SYMBOL(drm_dp_pcon_pps_override_buf);
/*
* drm_dp_pcon_pps_override_param() - Write PPS parameters to DSC encoder
* override registers
* @aux: DisplayPort AUX channel
* @pps_param: 3 Parameters (2 Bytes each) : Slice Width, Slice Height,
* bits_per_pixel.
*
* Returns 0 on success, else returns negative error code.
*/
int drm_dp_pcon_pps_override_param(struct drm_dp_aux *aux, u8 pps_param[6])
{
int ret;
ret = drm_dp_dpcd_write_data(aux, DP_PCON_HDMI_PPS_OVRD_SLICE_HEIGHT, &pps_param[0], 2);
if (ret < 0)
return ret;
ret = drm_dp_dpcd_write_data(aux, DP_PCON_HDMI_PPS_OVRD_SLICE_WIDTH, &pps_param[2], 2);
if (ret < 0)
return ret;
ret = drm_dp_dpcd_write_data(aux, DP_PCON_HDMI_PPS_OVRD_BPP, &pps_param[4], 2);
if (ret < 0)
return ret;
return drm_dp_pcon_configure_dsc_enc(aux, DP_PCON_ENC_PPS_OVERRIDE_EN_BUFFER);
}
EXPORT_SYMBOL(drm_dp_pcon_pps_override_param);
/*
* drm_dp_pcon_convert_rgb_to_ycbcr() - Configure the PCon to convert RGB to Ycbcr
* @aux: displayPort AUX channel
* @color_spc: Color-space/s for which conversion is to be enabled, 0 for disable.
*
* Returns 0 on success, else returns negative error code.
*/
int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8 color_spc)
{
int ret;
u8 buf;
ret = drm_dp_dpcd_read_byte(aux, DP_PROTOCOL_CONVERTER_CONTROL_2, &buf);
if (ret < 0)
return ret;
if (color_spc & DP_CONVERSION_RGB_YCBCR_MASK)
buf |= (color_spc & DP_CONVERSION_RGB_YCBCR_MASK);
else
buf &= ~DP_CONVERSION_RGB_YCBCR_MASK;
return drm_dp_dpcd_write_byte(aux, DP_PROTOCOL_CONVERTER_CONTROL_2, buf);
}
EXPORT_SYMBOL(drm_dp_pcon_convert_rgb_to_ycbcr);
/**
* drm_edp_backlight_set_level() - Set the backlight level of an eDP panel via AUX
* @aux: The DP AUX channel to use
* @bl: Backlight capability info from drm_edp_backlight_init()
* @level: The brightness level to set
*
* Sets the brightness level of an eDP panel's backlight. Note that the panel's backlight must
* already have been enabled by the driver by calling drm_edp_backlight_enable().
*
* Returns: %0 on success, negative error code on failure
*/
int drm_edp_backlight_set_level(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl,
u32 level)
{
int ret;
unsigned int offset = DP_EDP_BACKLIGHT_BRIGHTNESS_MSB;
u8 buf[3] = { 0 };
size_t len = 2;
/* The panel uses the PWM for controlling brightness levels */
if (!(bl->aux_set || bl->luminance_set))
return 0;
if (bl->luminance_set) {
level = level * 1000;
level &= 0xffffff;
buf[0] = (level & 0x0000ff);
buf[1] = (level & 0x00ff00) >> 8;
buf[2] = (level & 0xff0000) >> 16;
offset = DP_EDP_PANEL_TARGET_LUMINANCE_VALUE;
len = 3;
} else if (bl->lsb_reg_used) {
buf[0] = (level & 0xff00) >> 8;
buf[1] = (level & 0x00ff);
} else {
buf[0] = level;
}
ret = drm_dp_dpcd_write_data(aux, offset, buf, len);
if (ret < 0) {
drm_err(aux->drm_dev,
"%s: Failed to write aux backlight level: %d\n",
aux->name, ret);
return ret;
}
return 0;
}
EXPORT_SYMBOL(drm_edp_backlight_set_level);
static int
drm_edp_backlight_set_enable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl,
bool enable)
{
int ret;
u8 buf;
/* This panel uses the EDP_BL_PWR GPIO for enablement */
if (!bl->aux_enable)
return 0;
ret = drm_dp_dpcd_read_byte(aux, DP_EDP_DISPLAY_CONTROL_REGISTER, &buf);
if (ret < 0) {
drm_err(aux->drm_dev, "%s: Failed to read eDP display control register: %d\n",
aux->name, ret);
return ret;
}
if (enable)
buf |= DP_EDP_BACKLIGHT_ENABLE;
else
buf &= ~DP_EDP_BACKLIGHT_ENABLE;
ret = drm_dp_dpcd_write_byte(aux, DP_EDP_DISPLAY_CONTROL_REGISTER, buf);
if (ret < 0) {
drm_err(aux->drm_dev, "%s: Failed to write eDP display control register: %d\n",
aux->name, ret);
return ret;
}
return 0;
}
/**
* drm_edp_backlight_enable() - Enable an eDP panel's backlight using DPCD
* @aux: The DP AUX channel to use
* @bl: Backlight capability info from drm_edp_backlight_init()
* @level: The initial backlight level to set via AUX, if there is one
*
* This function handles enabling DPCD backlight controls on a panel over DPCD, while additionally
* restoring any important backlight state such as the given backlight level, the brightness byte
* count, backlight frequency, etc.
*
* Note that certain panels do not support being enabled or disabled via DPCD, but instead require
* that the driver handle enabling/disabling the panel through implementation-specific means using
* the EDP_BL_PWR GPIO. For such panels, &drm_edp_backlight_info.aux_enable will be set to %false,
* this function becomes a no-op, and the driver is expected to handle powering the panel on using
* the EDP_BL_PWR GPIO.
*
* Returns: %0 on success, negative error code on failure.
*/
int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl,
const u32 level)
{
int ret;
u8 dpcd_buf;
if (bl->aux_set)
dpcd_buf = DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
else
dpcd_buf = DP_EDP_BACKLIGHT_CONTROL_MODE_PWM;
if (bl->luminance_set)
dpcd_buf |= DP_EDP_PANEL_LUMINANCE_CONTROL_ENABLE;
if (bl->pwmgen_bit_count) {
ret = drm_dp_dpcd_write_byte(aux, DP_EDP_PWMGEN_BIT_COUNT, bl->pwmgen_bit_count);
if (ret < 0)
drm_dbg_kms(aux->drm_dev, "%s: Failed to write aux pwmgen bit count: %d\n",
aux->name, ret);
}
if (bl->pwm_freq_pre_divider) {
ret = drm_dp_dpcd_write_byte(aux, DP_EDP_BACKLIGHT_FREQ_SET,
bl->pwm_freq_pre_divider);
if (ret < 0)
drm_dbg_kms(aux->drm_dev,
"%s: Failed to write aux backlight frequency: %d\n",
aux->name, ret);
else
dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE;
}
ret = drm_dp_dpcd_write_byte(aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf);
if (ret < 0) {
drm_dbg_kms(aux->drm_dev, "%s: Failed to write aux backlight mode: %d\n",
aux->name, ret);
return ret < 0 ? ret : -EIO;
}
ret = drm_edp_backlight_set_level(aux, bl, level);
if (ret < 0)
return ret;
ret = drm_edp_backlight_set_enable(aux, bl, true);
if (ret < 0)
return ret;
return 0;
}
EXPORT_SYMBOL(drm_edp_backlight_enable);
/**
* drm_edp_backlight_disable() - Disable an eDP backlight using DPCD, if supported
* @aux: The DP AUX channel to use
* @bl: Backlight capability info from drm_edp_backlight_init()
*
* This function handles disabling DPCD backlight controls on a panel over AUX.
*
* Note that certain panels do not support being enabled or disabled via DPCD, but instead require
* that the driver handle enabling/disabling the panel through implementation-specific means using
* the EDP_BL_PWR GPIO. For such panels, &drm_edp_backlight_info.aux_enable will be set to %false,
* this function becomes a no-op, and the driver is expected to handle powering the panel off using
* the EDP_BL_PWR GPIO.
*
* Returns: %0 on success or no-op, negative error code on failure.
*/
int drm_edp_backlight_disable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl)
{
int ret;
ret = drm_edp_backlight_set_enable(aux, bl, false);
if (ret < 0)
return ret;
return 0;
}
EXPORT_SYMBOL(drm_edp_backlight_disable);
static inline int
drm_edp_backlight_probe_max(struct drm_dp_aux *aux, struct drm_edp_backlight_info *bl,
u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE])
{
int fxp, fxp_min, fxp_max, fxp_actual, f = 1;
int ret;
u8 pn, pn_min, pn_max;
if (!bl->aux_set)
return 0;
ret = drm_dp_dpcd_read_byte(aux, DP_EDP_PWMGEN_BIT_COUNT, &pn);
if (ret < 0) {
drm_dbg_kms(aux->drm_dev, "%s: Failed to read pwmgen bit count cap: %d\n",
aux->name, ret);
return -ENODEV;
}
pn &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
bl->max = (1 << pn) - 1;
if (!driver_pwm_freq_hz)
return 0;
/*
* Set PWM Frequency divider to match desired frequency provided by the driver.
* The PWM Frequency is calculated as 27Mhz / (F x P).
* - Where F = PWM Frequency Pre-Divider value programmed by field 7:0 of the
* EDP_BACKLIGHT_FREQ_SET register (DPCD Address 00728h)
* - Where P = 2^Pn, where Pn is the value programmed by field 4:0 of the
* EDP_PWMGEN_BIT_COUNT register (DPCD Address 00724h)
*/
/* Find desired value of (F x P)
* Note that, if F x P is out of supported range, the maximum value or minimum value will
* applied automatically. So no need to check that.
*/
fxp = DIV_ROUND_CLOSEST(1000 * DP_EDP_BACKLIGHT_FREQ_BASE_KHZ, driver_pwm_freq_hz);
/* Use highest possible value of Pn for more granularity of brightness adjustment while
* satisfying the conditions below.
* - Pn is in the range of Pn_min and Pn_max
* - F is in the range of 1 and 255
* - FxP is within 25% of desired value.
* Note: 25% is arbitrary value and may need some tweak.
*/
ret = drm_dp_dpcd_read_byte(aux, DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN, &pn_min);
if (ret < 0) {
drm_dbg_kms(aux->drm_dev, "%s: Failed to read pwmgen bit count cap min: %d\n",
aux->name, ret);
return 0;
}
ret = drm_dp_dpcd_read_byte(aux, DP_EDP_PWMGEN_BIT_COUNT_CAP_MAX, &pn_max);
if (ret < 0) {
drm_dbg_kms(aux->drm_dev, "%s: Failed to read pwmgen bit count cap max: %d\n",
aux->name, ret);
return 0;
}
pn_min &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
pn_max &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
/* Ensure frequency is within 25% of desired value */
fxp_min = DIV_ROUND_CLOSEST(fxp * 3, 4);
fxp_max = DIV_ROUND_CLOSEST(fxp * 5, 4);
if (fxp_min < (1 << pn_min) || (255 << pn_max) < fxp_max) {
drm_dbg_kms(aux->drm_dev,
"%s: Driver defined backlight frequency (%d) out of range\n",
aux->name, driver_pwm_freq_hz);
return 0;
}
for (pn = pn_max; pn >= pn_min; pn--) {
f = clamp(DIV_ROUND_CLOSEST(fxp, 1 << pn), 1, 255);
fxp_actual = f << pn;
if (fxp_min <= fxp_actual && fxp_actual <= fxp_max)
break;
}
ret = drm_dp_dpcd_write_byte(aux, DP_EDP_PWMGEN_BIT_COUNT, pn);
if (ret < 0) {
drm_dbg_kms(aux->drm_dev, "%s: Failed to write aux pwmgen bit count: %d\n",
aux->name, ret);
return 0;
}
bl->pwmgen_bit_count = pn;
bl->max = (1 << pn) - 1;
if (edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP) {
bl->pwm_freq_pre_divider = f;
drm_dbg_kms(aux->drm_dev, "%s: Using backlight frequency from driver (%dHz)\n",
aux->name, driver_pwm_freq_hz);
}
return 0;
}
static inline int
drm_edp_backlight_probe_state(struct drm_dp_aux *aux, struct drm_edp_backlight_info *bl,
u8 *current_mode)
{
int ret;
u8 buf[3];
u8 mode_reg;
ret = drm_dp_dpcd_read_byte(aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &mode_reg);
if (ret < 0) {
drm_dbg_kms(aux->drm_dev, "%s: Failed to read backlight mode: %d\n",
aux->name, ret);
return ret < 0 ? ret : -EIO;
}
*current_mode = (mode_reg & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK);
if (!bl->aux_set)
return 0;
if (*current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {
int size = 1 + bl->lsb_reg_used;
if (bl->luminance_set) {
ret = drm_dp_dpcd_read_data(aux, DP_EDP_PANEL_TARGET_LUMINANCE_VALUE,
buf, sizeof(buf));
if (ret < 0) {
drm_dbg_kms(aux->drm_dev,
"%s: Failed to read backlight level: %d\n",
aux->name, ret);
return ret;
}
/*
* Incase luminance is set we want to send the value back in nits but
* since DP_EDP_PANEL_TARGET_LUMINANCE stores values in millinits we
* need to divide by 1000.
*/
return (buf[0] | buf[1] << 8 | buf[2] << 16) / 1000;
} else {
ret = drm_dp_dpcd_read_data(aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
buf, size);
if (ret < 0) {
drm_dbg_kms(aux->drm_dev,
"%s: Failed to read backlight level: %d\n",
aux->name, ret);
return ret;
}
if (bl->lsb_reg_used)
return (buf[0] << 8) | buf[1];
else
return buf[0];
}
}
/*
* If we're not in DPCD control mode yet, the programmed brightness value is meaningless and
* the driver should assume max brightness
*/
return bl->max;
}
/**
* drm_edp_backlight_init() - Probe a display panel's TCON using the standard VESA eDP backlight
* interface.
* @aux: The DP aux device to use for probing
* @bl: The &drm_edp_backlight_info struct to fill out with information on the backlight
* @max_luminance: max luminance when need luminance is set as true
* @driver_pwm_freq_hz: Optional PWM frequency from the driver in hz
* @edp_dpcd: A cached copy of the eDP DPCD
* @current_level: Where to store the probed brightness level, if any
* @current_mode: Where to store the currently set backlight control mode
* @need_luminance: Tells us if a we want to manipulate backlight using luminance values
*
* Initializes a &drm_edp_backlight_info struct by probing @aux for it's backlight capabilities,
* along with also probing the current and maximum supported brightness levels.
*
* If @driver_pwm_freq_hz is non-zero, this will be used as the backlight frequency. Otherwise, the
* default frequency from the panel is used.
*
* Returns: %0 on success, negative error code on failure.
*/
int
drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info *bl,
u32 max_luminance,
u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE],
u32 *current_level, u8 *current_mode, bool need_luminance)
{
int ret;
if (edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP)
bl->aux_enable = true;
if (edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)
bl->aux_set = true;
if (edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
bl->lsb_reg_used = true;
if ((edp_dpcd[0] & DP_EDP_15) && edp_dpcd[3] &
(DP_EDP_PANEL_LUMINANCE_CONTROL_CAPABLE) && need_luminance)
bl->luminance_set = true;
/* Sanity check caps */
if (!bl->aux_set && !(edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP) &&
!bl->luminance_set) {
drm_dbg_kms(aux->drm_dev,
"%s: Panel does not support AUX, PWM or luminance-based brightness control. Aborting\n",
aux->name);
return -EINVAL;
}
if (bl->luminance_set) {
bl->max = max_luminance;
} else {
ret = drm_edp_backlight_probe_max(aux, bl, driver_pwm_freq_hz, edp_dpcd);
if (ret < 0)
return ret;
}
ret = drm_edp_backlight_probe_state(aux, bl, current_mode);
if (ret < 0)
return ret;
*current_level = ret;
drm_dbg_kms(aux->drm_dev,
"%s: Found backlight: aux_set=%d aux_enable=%d mode=%d\n",
aux->name, bl->aux_set, bl->aux_enable, *current_mode);
if (bl->aux_set) {
drm_dbg_kms(aux->drm_dev,
"%s: Backlight caps: level=%d/%d pwm_freq_pre_divider=%d lsb_reg_used=%d\n",
aux->name, *current_level, bl->max, bl->pwm_freq_pre_divider,
bl->lsb_reg_used);
}
return 0;
}
EXPORT_SYMBOL(drm_edp_backlight_init);
#if IS_BUILTIN(CONFIG_BACKLIGHT_CLASS_DEVICE) || \
(IS_MODULE(CONFIG_DRM_KMS_HELPER) && IS_MODULE(CONFIG_BACKLIGHT_CLASS_DEVICE))
static int dp_aux_backlight_update_status(struct backlight_device *bd)
{
struct dp_aux_backlight *bl = bl_get_data(bd);
u16 brightness = backlight_get_brightness(bd);
int ret = 0;
if (!backlight_is_blank(bd)) {
if (!bl->enabled) {
drm_edp_backlight_enable(bl->aux, &bl->info, brightness);
bl->enabled = true;
return 0;
}
ret = drm_edp_backlight_set_level(bl->aux, &bl->info, brightness);
} else {
if (bl->enabled) {
drm_edp_backlight_disable(bl->aux, &bl->info);
bl->enabled = false;
}
}
return ret;
}
static const struct backlight_ops dp_aux_bl_ops = {
.update_status = dp_aux_backlight_update_status,
};
/**
* drm_panel_dp_aux_backlight - create and use DP AUX backlight
* @panel: DRM panel
* @aux: The DP AUX channel to use
*
* Use this function to create and handle backlight if your panel
* supports backlight control over DP AUX channel using DPCD
* registers as per VESA's standard backlight control interface.
*
* When the panel is enabled backlight will be enabled after a
* successful call to &drm_panel_funcs.enable()
*
* When the panel is disabled backlight will be disabled before the
* call to &drm_panel_funcs.disable().
*
* A typical implementation for a panel driver supporting backlight
* control over DP AUX will call this function at probe time.
* Backlight will then be handled transparently without requiring
* any intervention from the driver.
*
* drm_panel_dp_aux_backlight() must be called after the call to drm_panel_init().
*
* Return: 0 on success or a negative error code on failure.
*/
int drm_panel_dp_aux_backlight(struct drm_panel *panel, struct drm_dp_aux *aux)
{
struct dp_aux_backlight *bl;
struct backlight_properties props = { 0 };
u32 current_level;
u8 current_mode;
u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE];
int ret;
if (!panel || !panel->dev || !aux)
return -EINVAL;
ret = drm_dp_dpcd_read_data(aux, DP_EDP_DPCD_REV, edp_dpcd,
EDP_DISPLAY_CTL_CAP_SIZE);
if (ret < 0)
return ret;
if (!drm_edp_backlight_supported(edp_dpcd)) {
DRM_DEV_INFO(panel->dev, "DP AUX backlight is not supported\n");
return 0;
}
bl = devm_kzalloc(panel->dev, sizeof(*bl), GFP_KERNEL);
if (!bl)
return -ENOMEM;
bl->aux = aux;
ret = drm_edp_backlight_init(aux, &bl->info, 0, 0, edp_dpcd,
&current_level, &current_mode, false);
if (ret < 0)
return ret;
props.type = BACKLIGHT_RAW;
props.brightness = current_level;
props.max_brightness = bl->info.max;
bl->base = devm_backlight_device_register(panel->dev, "dp_aux_backlight",
panel->dev, bl,
&dp_aux_bl_ops, &props);
if (IS_ERR(bl->base))
return PTR_ERR(bl->base);
backlight_disable(bl->base);
panel->backlight = bl->base;
return 0;
}
EXPORT_SYMBOL(drm_panel_dp_aux_backlight);
#endif
/* See DP Standard v2.1 2.6.4.4.1.1, 2.8.4.4, 2.8.7 */
static int drm_dp_link_data_symbol_cycles(int lane_count, int pixels,
int bpp_x16, int symbol_size,
bool is_mst)
{
int cycles = DIV_ROUND_UP(pixels * bpp_x16, 16 * symbol_size * lane_count);
int align = is_mst ? 4 / lane_count : 1;
return ALIGN(cycles, align);
}
/**
* drm_dp_link_symbol_cycles - calculate the link symbol count with/without dsc
* @lane_count: DP link lane count
* @pixels: number of pixels in a scanline
* @dsc_slice_count: number of slices for DSC or '0' for non-DSC
* @bpp_x16: bits per pixel in .4 binary fixed format
* @symbol_size: DP symbol size
* @is_mst: %true for MST and %false for SST
*
* Calculate the link symbol cycles for both DSC (@dsc_slice_count !=0) and
* non-DSC case (@dsc_slice_count == 0) and return the count.
*/
int drm_dp_link_symbol_cycles(int lane_count, int pixels, int dsc_slice_count,
int bpp_x16, int symbol_size, bool is_mst)
{
int slice_count = dsc_slice_count ? : 1;
int slice_pixels = DIV_ROUND_UP(pixels, slice_count);
int slice_data_cycles = drm_dp_link_data_symbol_cycles(lane_count,
slice_pixels,
bpp_x16,
symbol_size,
is_mst);
int slice_eoc_cycles = 0;
if (dsc_slice_count)
slice_eoc_cycles = is_mst ? 4 / lane_count : 1;
return slice_count * (slice_data_cycles + slice_eoc_cycles);
}
EXPORT_SYMBOL(drm_dp_link_symbol_cycles);
/**
* drm_dp_bw_overhead - Calculate the BW overhead of a DP link stream
* @lane_count: DP link lane count
* @hactive: pixel count of the active period in one scanline of the stream
* @dsc_slice_count: number of slices for DSC or '0' for non-DSC
* @bpp_x16: bits per pixel in .4 binary fixed point
* @flags: DRM_DP_OVERHEAD_x flags
*
* Calculate the BW allocation overhead of a DP link stream, depending
* on the link's
* - @lane_count
* - SST/MST mode (@flags / %DRM_DP_OVERHEAD_MST)
* - symbol size (@flags / %DRM_DP_OVERHEAD_UHBR)
* - FEC mode (@flags / %DRM_DP_OVERHEAD_FEC)
* - SSC/REF_CLK mode (@flags / %DRM_DP_OVERHEAD_SSC_REF_CLK)
* as well as the stream's
* - @hactive timing
* - @bpp_x16 color depth
* - compression mode (@dsc_slice_count != 0)
* Note that this overhead doesn't account for the 8b/10b, 128b/132b
* channel coding efficiency, for that see
* @drm_dp_link_bw_channel_coding_efficiency().
*
* Returns the overhead as 100% + overhead% in 1ppm units.
*/
int drm_dp_bw_overhead(int lane_count, int hactive,
int dsc_slice_count,
int bpp_x16, unsigned long flags)
{
int symbol_size = flags & DRM_DP_BW_OVERHEAD_UHBR ? 32 : 8;
bool is_mst = flags & DRM_DP_BW_OVERHEAD_MST;
u32 overhead = 1000000;
int symbol_cycles;
if (lane_count == 0 || hactive == 0 || bpp_x16 == 0) {
DRM_DEBUG_KMS("Invalid BW overhead params: lane_count %d, hactive %d, bpp_x16 " FXP_Q4_FMT "\n",
lane_count, hactive,
FXP_Q4_ARGS(bpp_x16));
return 0;
}
/*
* DP Standard v2.1 2.6.4.1
* SSC downspread and ref clock variation margin:
* 5300ppm + 300ppm ~ 0.6%
*/
if (flags & DRM_DP_BW_OVERHEAD_SSC_REF_CLK)
overhead += 6000;
/*
* DP Standard v2.1 2.6.4.1.1, 3.5.1.5.4:
* FEC symbol insertions for 8b/10b channel coding:
* After each 250 data symbols on 2-4 lanes:
* 250 LL + 5 FEC_PARITY_PH + 1 CD_ADJ (256 byte FEC block)
* After each 2 x 250 data symbols on 1 lane:
* 2 * 250 LL + 11 FEC_PARITY_PH + 1 CD_ADJ (512 byte FEC block)
* After 256 (2-4 lanes) or 128 (1 lane) FEC blocks:
* 256 * 256 bytes + 1 FEC_PM
* or
* 128 * 512 bytes + 1 FEC_PM
* (256 * 6 + 1) / (256 * 250) = 2.4015625 %
*/
if (flags & DRM_DP_BW_OVERHEAD_FEC)
overhead += 24016;
/*
* DP Standard v2.1 2.7.9, 5.9.7
* The FEC overhead for UHBR is accounted for in its 96.71% channel
* coding efficiency.
*/
WARN_ON((flags & DRM_DP_BW_OVERHEAD_UHBR) &&
(flags & DRM_DP_BW_OVERHEAD_FEC));
symbol_cycles = drm_dp_link_symbol_cycles(lane_count, hactive,
dsc_slice_count,
bpp_x16, symbol_size,
is_mst);
return DIV_ROUND_UP_ULL(mul_u32_u32(symbol_cycles * symbol_size * lane_count,
overhead * 16),
hactive * bpp_x16);
}
EXPORT_SYMBOL(drm_dp_bw_overhead);
/**
* drm_dp_bw_channel_coding_efficiency - Get a DP link's channel coding efficiency
* @is_uhbr: Whether the link has a 128b/132b channel coding
*
* Return the channel coding efficiency of the given DP link type, which is
* either 8b/10b or 128b/132b (aka UHBR). The corresponding overhead includes
* the 8b -> 10b, 128b -> 132b pixel data to link symbol conversion overhead
* and for 128b/132b any link or PHY level control symbol insertion overhead
* (LLCP, FEC, PHY sync, see DP Standard v2.1 3.5.2.18). For 8b/10b the
* corresponding FEC overhead is BW allocation specific, included in the value
* returned by drm_dp_bw_overhead().
*
* Returns the efficiency in the 100%/coding-overhead% ratio in
* 1ppm units.
*/
int drm_dp_bw_channel_coding_efficiency(bool is_uhbr)
{
if (is_uhbr)
return 967100;
else
/*
* Note that on 8b/10b MST the efficiency is only
* 78.75% due to the 1 out of 64 MTPH packet overhead,
* not accounted for here.
*/
return 800000;
}
EXPORT_SYMBOL(drm_dp_bw_channel_coding_efficiency);
/**
* drm_dp_max_dprx_data_rate - Get the max data bandwidth of a DPRX sink
* @max_link_rate: max DPRX link rate in 10kbps units
* @max_lanes: max DPRX lane count
*
* Given a link rate and lanes, get the data bandwidth.
*
* Data bandwidth is the actual payload rate, which depends on the data
* bandwidth efficiency and the link rate.
*
* Note that protocol layers above the DPRX link level considered here can
* further limit the maximum data rate. Such layers are the MST topology (with
* limits on the link between the source and first branch device as well as on
* the whole MST path until the DPRX link) and (Thunderbolt) DP tunnels -
* which in turn can encapsulate an MST link with its own limit - with each
* SST or MST encapsulated tunnel sharing the BW of a tunnel group.
*
* Returns the maximum data rate in kBps units.
*/
int drm_dp_max_dprx_data_rate(int max_link_rate, int max_lanes)
{
int ch_coding_efficiency =
drm_dp_bw_channel_coding_efficiency(drm_dp_is_uhbr_rate(max_link_rate));
return DIV_ROUND_DOWN_ULL(mul_u32_u32(max_link_rate * 10 * max_lanes,
ch_coding_efficiency),
1000000 * 8);
}
EXPORT_SYMBOL(drm_dp_max_dprx_data_rate);
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