linux/drivers/gpu/drm/udl/udl_drv.c
Thomas Zimmermann e7a1cbca0b drm/gem-shmem: Do not map s/g table by default
The vast majority of drivers that use GEM-SHMEM helpers do not use
an s/g table for imported buffers; specifically all drivers that use
DRM_GEM_SHMEM_DRIVER_OPS. Therefore convert the initializer macro
to DRM_GEM_SHMEM_DRIVER_OPS_NO_MAP_SGT and remove the latter. This
helps to avoid swiotbl errors, such as seen with some Aspeed systems

  ast 0000:07:00.0: swiotlb buffer is full (sz: 3145728 bytes), total 32768 (slots), used 0 (slots)

The error is caused by the system's limited DMA capabilities and can
happen with any GEM-SHMEM-based driver. It results in a performance
penalty.

In the case of vgem and vkms, the devices do not support DMA at all,
which can result in failure to map the buffer object into the kernel's
address space. [1][2] Avoiding the s/g table fixes this problem.

The other drivers based on GEM-SHMEM, imagination, lima, panfrost,
panthor, v3d and virtio, use the s/g table of imported buffers. Neither
driver uses the default initializer, so they won't be affected by
this change.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reported-by: Zenghui Yu <zenghui.yu@linux.dev>
Closes: https://lore.kernel.org/dri-devel/6d22bce3-4533-4cfa-96ba-64352b715741@linux.dev/ # [1]
Reported-by: José Expósito <jose.exposito89@gmail.com>
Closes: https://lore.kernel.org/dri-devel/20250311172054.2903-1-jose.exposito89@gmail.com/ # [2]
Tested-by: Zenghui Yu <zenghui.yu@linux.dev>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Link: https://lore.kernel.org/r/20250630143537.309052-1-tzimmermann@suse.de
2025-07-07 15:23:41 +02:00

149 lines
3.5 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2012 Red Hat
*/
#include <linux/module.h>
#include <drm/clients/drm_client_setup.h>
#include <drm/drm_drv.h>
#include <drm/drm_fbdev_shmem.h>
#include <drm/drm_file.h>
#include <drm/drm_gem_shmem_helper.h>
#include <drm/drm_managed.h>
#include <drm/drm_modeset_helper.h>
#include <drm/drm_ioctl.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_print.h>
#include "udl_drv.h"
static int udl_usb_suspend(struct usb_interface *interface,
pm_message_t message)
{
struct drm_device *dev = usb_get_intfdata(interface);
struct udl_device *udl = to_udl(dev);
int ret;
ret = drm_mode_config_helper_suspend(dev);
if (ret)
return ret;
udl_sync_pending_urbs(udl);
return 0;
}
static int udl_usb_resume(struct usb_interface *interface)
{
struct drm_device *dev = usb_get_intfdata(interface);
return drm_mode_config_helper_resume(dev);
}
static int udl_usb_reset_resume(struct usb_interface *interface)
{
struct drm_device *dev = usb_get_intfdata(interface);
struct udl_device *udl = to_udl(dev);
udl_select_std_channel(udl);
return drm_mode_config_helper_resume(dev);
}
DEFINE_DRM_GEM_FOPS(udl_driver_fops);
static const struct drm_driver driver = {
.driver_features = DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
/* GEM hooks */
.fops = &udl_driver_fops,
DRM_GEM_SHMEM_DRIVER_OPS,
DRM_FBDEV_SHMEM_DRIVER_OPS,
.name = DRIVER_NAME,
.desc = DRIVER_DESC,
.major = DRIVER_MAJOR,
.minor = DRIVER_MINOR,
.patchlevel = DRIVER_PATCHLEVEL,
};
static struct udl_device *udl_driver_create(struct usb_interface *interface)
{
struct udl_device *udl;
int r;
udl = devm_drm_dev_alloc(&interface->dev, &driver,
struct udl_device, drm);
if (IS_ERR(udl))
return udl;
r = udl_init(udl);
if (r)
return ERR_PTR(r);
usb_set_intfdata(interface, udl);
return udl;
}
static int udl_usb_probe(struct usb_interface *interface,
const struct usb_device_id *id)
{
int r;
struct udl_device *udl;
udl = udl_driver_create(interface);
if (IS_ERR(udl))
return PTR_ERR(udl);
r = drm_dev_register(&udl->drm, 0);
if (r)
return r;
DRM_INFO("Initialized udl on minor %d\n", udl->drm.primary->index);
drm_client_setup(&udl->drm, NULL);
return 0;
}
static void udl_usb_disconnect(struct usb_interface *interface)
{
struct drm_device *dev = usb_get_intfdata(interface);
struct udl_device *udl = to_udl(dev);
drm_dev_unplug(dev);
udl_drop_usb(udl);
}
/*
* There are many DisplayLink-based graphics products, all with unique PIDs.
* So we match on DisplayLink's VID + Vendor-Defined Interface Class (0xff)
* We also require a match on SubClass (0x00) and Protocol (0x00),
* which is compatible with all known USB 2.0 era graphics chips and firmware,
* but allows DisplayLink to increment those for any future incompatible chips
*/
static const struct usb_device_id id_table[] = {
{.idVendor = 0x17e9, .bInterfaceClass = 0xff,
.bInterfaceSubClass = 0x00,
.bInterfaceProtocol = 0x00,
.match_flags = USB_DEVICE_ID_MATCH_VENDOR |
USB_DEVICE_ID_MATCH_INT_CLASS |
USB_DEVICE_ID_MATCH_INT_SUBCLASS |
USB_DEVICE_ID_MATCH_INT_PROTOCOL,},
{},
};
MODULE_DEVICE_TABLE(usb, id_table);
static struct usb_driver udl_driver = {
.name = "udl",
.probe = udl_usb_probe,
.disconnect = udl_usb_disconnect,
.suspend = udl_usb_suspend,
.resume = udl_usb_resume,
.reset_resume = udl_usb_reset_resume,
.id_table = id_table,
};
module_usb_driver(udl_driver);
MODULE_DESCRIPTION("KMS driver for the USB displaylink video adapters");
MODULE_LICENSE("GPL");