[SRU][resolute][PATCH 0/1] drm/xe/display: allow external dma-buf framebuffers

[ChunAn Wu]

BugLink: https://bugs.launchpad.net/bugs/2158605

[Impact]
Screen garbage can show when running glxgears fullscreen on affected
Intel graphics systems.

The Launchpad report says it happens about 1 in 3 runs.

[Fix]
Skip the SCANOUT flag and VM_BIND checks for external dma-buf imports
in the xe display framebuffer setup and pin paths.

For imported sg buffers, CPU caching is controlled by the exporter.
The patch keeps the existing checks for local buffers.

This patch is from upstream Patchwork, not yet merged:
https://patchwork.freedesktop.org/patch/732636/

[Test Plan]
Run the fullscreen glxgears test 10 times:
$ glxgears -fullscreen

Or run the matching checkbox test for the affected GPU:
$ checkbox-cli run graphics/2_valid_glxgears_fullscreen_PCI_ID_<affected-gpu>

Without patch: screen shows garbage during the fullscreen glxgears test.
With patch: fullscreen glxgears completes without screen garbage.

[Where problems could occur]
Could break external dma-buf framebuffer setup in the xe display driver.

If the sg-buffer exception is wrong, imported framebuffers could be
accepted when they should be rejected. This could show as display
corruption, failed framebuffer creation, or xe framebuffer pinning
warnings.

[Other Info]
SRU target: linux-oem-6.17.
The patch is not in an upstream kernel release yet.

Matthew Auld (1):
  UBUNTU: SAUCE: drm/xe/display: skip FORCE_WC and vm_bound check for external dma-bufs

 drivers/gpu/drm/xe/display/intel_fb_bo.c | 3 ++-
 drivers/gpu/drm/xe/display/xe_fb_pin.c   | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

-- 
2.34.1