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drm: Use USB controller's DMA mask when importing dmabufs

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commit 659ab7a49cbebe0deffcbe1f9560e82006b21817 upstream.

USB devices cannot perform DMA and hence have no dma_mask set in their
device structure. Therefore importing dmabuf into a USB-based driver
fails, which breaks joining and mirroring of display in X11.

For USB devices, pick the associated USB controller as attachment device.
This allows the DRM import helpers to perform the DMA setup. If the DMA
controller does not support DMA transfers, we're out of luck and cannot
import. Our current USB-based DRM drivers don't use DMA, so the actual
DMA device is not important.

Tested by joining/mirroring displays of udl and radeon under Gnome/X11.

v8:
	* release dmadev if device initialization fails (Noralf)
	* fix commit description (Noralf)
v7:
	* fix use-before-init bug in gm12u320 (Dan)
v6:
	* implement workaround in DRM drivers and hold reference to
	  DMA device while USB device is in use
	* remove dev_is_usb() (Greg)
	* collapse USB helper into usb_intf_get_dma_device() (Alan)
	* integrate Daniel's TODO statement (Daniel)
	* fix typos (Greg)
v5:
	* provide a helper for USB interfaces (Alan)
	* add FIXME item to documentation and TODO list (Daniel)
v4:
	* implement workaround with USB helper functions (Greg)
	* use struct usb_device->bus->sysdev as DMA device (Takashi)
v3:
	* drop gem_create_object
	* use DMA mask of USB controller, if any (Daniel, Christian, Noralf)
v2:
	* move fix to importer side (Christian, Daniel)
	* update SHMEM and CMA helpers for new PRIME callbacks

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 6eb0233ec2 ("usb: don't inherity DMA properties for USB devices")
Tested-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org> # v5.10+
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210303133229.3288-1-tzimmermann@suse.de
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Zimmermann
2021-03-03 14:32:29 +01:00
committed by Greg Kroah-Hartman
parent 5e9b011525
commit 915f2f8cad
7 changed files with 119 additions and 8 deletions
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17
drivers/gpu/drm/udl/udl_drv.c
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@@ -32,6 +32,22 @@ static int udl_usb_resume(struct usb_interface *interface)
return drm_mode_config_helper_resume(dev);
}
/*
* FIXME: Dma-buf sharing requires DMA support by the importing device.
* This function is a workaround to make USB devices work as well.
* See todo.rst for how to fix the issue in the dma-buf framework.
*/
static struct drm_gem_object *udl_driver_gem_prime_import(struct drm_device *dev,
struct dma_buf *dma_buf)
{
struct udl_device *udl = to_udl(dev);
if (!udl->dmadev)
return ERR_PTR(-ENODEV);
return drm_gem_prime_import_dev(dev, dma_buf, udl->dmadev);
}
DEFINE_DRM_GEM_FOPS(udl_driver_fops);
static struct drm_driver driver = {
@@ -42,6 +58,7 @@ static struct drm_driver driver = {
.fops = &udl_driver_fops,
DRM_GEM_SHMEM_DRIVER_OPS,
.gem_prime_import = udl_driver_gem_prime_import,
.name = DRIVER_NAME,
.desc = DRIVER_DESC,