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backlight: pwm_bl: Switch to using "atomic" PWM API

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The "atomic" API allows us to configure PWM period and duty_cycle and
enable it in one call.

The patch also moves the pwm_init_state just before any use of the
pwm_state struct, this fixes a potential bug where pwm_get_state
can be called before pwm_init_state.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Enric Balletbo i Serra 2018-08-14 18:50:59 +02:00 committed by Lee Jones
parent 0b193400b3
commit e6bcca0890
1 changed files with 42 additions and 39 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

81
drivers/video/backlight/pwm_bl.c
View file

@ -28,10 +28,8 @@
struct pwm_bl_data { struct pwm_bl_data {
struct pwm_device *pwm; struct pwm_device *pwm;
struct device *dev; struct device *dev;
unsigned int period;
unsigned int lth_brightness; unsigned int lth_brightness;
unsigned int *levels; unsigned int *levels;
bool enabled;
struct regulator *power_supply; struct regulator *power_supply;
struct gpio_desc *enable_gpio; struct gpio_desc *enable_gpio;
unsigned int scale; unsigned int scale;
@ -46,31 +44,35 @@ struct pwm_bl_data {
void (*exit)(struct device *); void (*exit)(struct device *);
}; };
static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness) static void pwm_backlight_power_on(struct pwm_bl_data *pb)
{ {
struct pwm_state state;
int err; int err;
if (pb->enabled) pwm_get_state(pb->pwm, &state);
if (state.enabled)
return; return;
err = regulator_enable(pb->power_supply); err = regulator_enable(pb->power_supply);
if (err < 0) if (err < 0)
dev_err(pb->dev, "failed to enable power supply\n"); dev_err(pb->dev, "failed to enable power supply\n");
pwm_enable(pb->pwm); state.enabled = true;
pwm_apply_state(pb->pwm, &state);
if (pb->post_pwm_on_delay) if (pb->post_pwm_on_delay)
msleep(pb->post_pwm_on_delay); msleep(pb->post_pwm_on_delay);
if (pb->enable_gpio) if (pb->enable_gpio)
gpiod_set_value_cansleep(pb->enable_gpio, 1); gpiod_set_value_cansleep(pb->enable_gpio, 1);
pb->enabled = true;
} }
static void pwm_backlight_power_off(struct pwm_bl_data *pb) static void pwm_backlight_power_off(struct pwm_bl_data *pb)
{ {
if (!pb->enabled) struct pwm_state state;
pwm_get_state(pb->pwm, &state);
if (!state.enabled)
return; return;
if (pb->enable_gpio) if (pb->enable_gpio)
@ -79,24 +81,27 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
if (pb->pwm_off_delay) if (pb->pwm_off_delay)
msleep(pb->pwm_off_delay); msleep(pb->pwm_off_delay);
pwm_config(pb->pwm, 0, pb->period); state.enabled = false;
pwm_disable(pb->pwm); state.duty_cycle = 0;
pwm_apply_state(pb->pwm, &state);
regulator_disable(pb->power_supply); regulator_disable(pb->power_supply);
pb->enabled = false;
} }
static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness) static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
{ {
unsigned int lth = pb->lth_brightness; unsigned int lth = pb->lth_brightness;
struct pwm_state state;
u64 duty_cycle; u64 duty_cycle;
pwm_get_state(pb->pwm, &state);
if (pb->levels) if (pb->levels)
duty_cycle = pb->levels[brightness]; duty_cycle = pb->levels[brightness];
else else
duty_cycle = brightness; duty_cycle = brightness;
duty_cycle *= pb->period - lth; duty_cycle *= state.period - lth;
do_div(duty_cycle, pb->scale); do_div(duty_cycle, pb->scale);
return duty_cycle + lth; return duty_cycle + lth;
@ -106,7 +111,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
{ {
struct pwm_bl_data *pb = bl_get_data(bl); struct pwm_bl_data *pb = bl_get_data(bl);
int brightness = bl->props.brightness; int brightness = bl->props.brightness;
int duty_cycle; struct pwm_state state;
if (bl->props.power != FB_BLANK_UNBLANK || if (bl->props.power != FB_BLANK_UNBLANK ||
bl->props.fb_blank != FB_BLANK_UNBLANK || bl->props.fb_blank != FB_BLANK_UNBLANK ||
@ -117,9 +122,10 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
brightness = pb->notify(pb->dev, brightness); brightness = pb->notify(pb->dev, brightness);
if (brightness > 0) { if (brightness > 0) {
duty_cycle = compute_duty_cycle(pb, brightness); pwm_get_state(pb->pwm, &state);
pwm_config(pb->pwm, duty_cycle, pb->period); state.duty_cycle = compute_duty_cycle(pb, brightness);
pwm_backlight_power_on(pb, brightness); pwm_apply_state(pb->pwm, &state);
pwm_backlight_power_on(pb);
} else } else
pwm_backlight_power_off(pb); pwm_backlight_power_off(pb);
@ -447,7 +453,6 @@ static int pwm_backlight_probe(struct platform_device *pdev)
struct device_node *node = pdev->dev.of_node; struct device_node *node = pdev->dev.of_node;
struct pwm_bl_data *pb; struct pwm_bl_data *pb;
struct pwm_state state; struct pwm_state state;
struct pwm_args pargs;
unsigned int i; unsigned int i;
int ret; int ret;
@ -478,7 +483,6 @@ static int pwm_backlight_probe(struct platform_device *pdev)
pb->check_fb = data->check_fb; pb->check_fb = data->check_fb;
pb->exit = data->exit; pb->exit = data->exit;
pb->dev = &pdev->dev; pb->dev = &pdev->dev;
pb->enabled = false;
pb->post_pwm_on_delay = data->post_pwm_on_delay; pb->post_pwm_on_delay = data->post_pwm_on_delay;
pb->pwm_off_delay = data->pwm_off_delay; pb->pwm_off_delay = data->pwm_off_delay;
@ -539,10 +543,26 @@ static int pwm_backlight_probe(struct platform_device *pdev)
dev_dbg(&pdev->dev, "got pwm for backlight\n"); dev_dbg(&pdev->dev, "got pwm for backlight\n");
if (!data->levels) { /* Sync up PWM state. */
/* Get the PWM period (in nanoseconds) */ pwm_init_state(pb->pwm, &state);
pwm_get_state(pb->pwm, &state);
/*
* The DT case will set the pwm_period_ns field to 0 and store the
* period, parsed from the DT, in the PWM device. For the non-DT case,
* set the period from platform data if it has not already been set
* via the PWM lookup table.
*/
if (!state.period && (data->pwm_period_ns > 0))
state.period = data->pwm_period_ns;
ret = pwm_apply_state(pb->pwm, &state);
if (ret) {
dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
ret);
goto err_alloc;
}
if (!data->levels) {
ret = pwm_backlight_brightness_default(&pdev->dev, data, ret = pwm_backlight_brightness_default(&pdev->dev, data,
state.period); state.period);
if (ret < 0) { if (ret < 0) {
@ -559,24 +579,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
pb->levels = data->levels; pb->levels = data->levels;
} }
/* pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
* FIXME: pwm_apply_args() should be removed when switching to
* the atomic PWM API.
*/
pwm_apply_args(pb->pwm);
/*
* The DT case will set the pwm_period_ns field to 0 and store the
* period, parsed from the DT, in the PWM device. For the non-DT case,
* set the period from platform data if it has not already been set
* via the PWM lookup table.
*/
pwm_get_args(pb->pwm, &pargs);
pb->period = pargs.period;
if (!pb->period && (data->pwm_period_ns > 0))
pb->period = data->pwm_period_ns;
pb->lth_brightness = data->lth_brightness * (pb->period / pb->scale);
memset(&props, 0, sizeof(struct backlight_properties)); memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_RAW; props.type = BACKLIGHT_RAW;