[Bug 105720] screen corruption using SNA and TearFree on Intel GeminiLake

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=105720

--- Comment #35 from Clinton Taylor <clinton.a.taylor at intel.com> ---
(In reply to Chris Wilson from comment #34)
> Created attachment 138556 [details] [review]
> Reorder vblank/flip event handler
> 
> I do wonder if "sna: Defer submission of the next shadow frame until halfway
> through" wasn't that far off the truth. Please try the attached diff (3
> patches rolled into one), surmised by
> 
>     sna: Reorder vblank/flip event handling to avoid TearFree recursion
>     
>     TearFree wants to grab the most recently used scanout for rendering the
>     next frame into. If the flip event was still pending, we would then
>     query the drm event buffer for any pending completions, but this would
>     proceed to execute all the other events before the flip events as well.
>     Since we they were out of sequence, we pushed them into a buffer to
>     execute afterwards, however we forgot the side effects of the flip
>     handlers, for example see commit af36a4ab78cc ("sna: Defer submission
>     of the next shadow frame until halfway through") and that there may have
>     been events read from drm into a local buffer inside sna_mode_wakeup()
>     that haven't been processed yet.
>     
>     Eliminate the need for calling sna_mode_wakeup() by ensuring that all
>     flip events have been completed first before handing the vblank
>     callbacks and potential drawing, ensuring the correct ordering.
>     
>     References: https://bugs.freedesktop.org/show_bug.cgi?id=105720
>     Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Issue still occurs with this patch

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