** Description changed:
SRU Justification:
[ Impact ]
On AMD systems with DCN graphics, garbled display artifacts and horizontal
flickering occur when switching workspaces or playing video.
This is caused by a race condition where a page flip completion event is
delivered to userspace before the hardware has latched the flip.
Userspace then renders to the active display buffer, causing visual
corruption. PSR and Replay features widen this window.
[ Fix ]
- Backport upstream commit 48ab86360af117123eb1b15e38f068acf3826400
("drm/amd/display: check GRPH_FLIP status before sending event"):
- - Arm flip completion only after hardware programming completes.
- - Query hardware flip-pending status directly via
dc_get_flip_pending_on_otg().
- - Only deliver completion in the VUPDATE_NO_LOCK handler once hardware
confirms the flip is complete.
- - Optimistically send the event immediately if hardware latched during
programming.
+ Backport upstream commits:
+ - 8382cd234981 ("drm/amd/display: consolidate DCN vblank/flip handling onto
vupdate_no_lock"):
+ - Consolidate DCN vblank and flip handling onto VUPDATE_NO_LOCK.
+ - 48ab86360af1 ("drm/amd/display: check GRPH_FLIP status before sending
event"):
+ - Arm flip completion only after hardware programming completes.
+ - Query hardware flip-pending status directly via
dc_get_flip_pending_on_otg().
+ - Only deliver completion in the VUPDATE_NO_LOCK handler once hardware
confirms the flip is complete.
+ - Optimistically send the event immediately if hardware latched during
programming.
+ - 8419331e64d9 ("drm/amd/display: Exit idle optimizations before
programming"):
+ - Grab reference on vblank counter prior to workqueue flush and hardware
programming to exit PSR/IPS idle optimizations cleanly.
[ Test Plan ]
1. On an AMD system with DCN graphics, switch repeatedly between workspaces
and play video.
2. Without the fix: Garbled display artifacts appear frequently.
3. With the fix: Workspaces switch smoothly with no screen corruption.
[ Where problems could occur ]
- Changes affect the amdgpu display page flip completion path. If flip status
is misreported, page flip events could be delayed or missed, causing frame
drops or stutter.
+ Changes affect the amdgpu display page flip completion and idle optimization
paths. If flip status is misreported, page flip events could be delayed or
missed, causing frame drops or stutter.
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https://bugs.launchpad.net/bugs/2166730
Title:
[SRU] amdgpu: Fix garbled display when switching workspaces
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