Re: [Intel-gfx] [Intel-xe] [PATCH] drm/xe/display: Do not use i915 frontbuffer tracking implementation

[Maarten Lankhorst <maarten.lankhorst@linux.intel.com>]

On 2023-03-06 21:58, Ville Syrjälä wrote:
> On Mon, Mar 06, 2023 at 09:23:50PM +0100, Maarten Lankhorst wrote:
>> Hey,
>>
>> On 2023-03-06 16:23, Souza, Jose wrote:
>>> On Mon, 2023-03-06 at 15:16 +0100, Maarten Lankhorst wrote:
>>>> As a fallback if we decide not to merge the frontbuffer tracking, allow
>>>> i915 to keep its own implementation, and do the right thing in Xe.
>>>>
>>>> The frontbuffer tracking for Xe is still done per-fb, while i915 can
>>>> keep doing the weird intel_frontbuffer + i915_active thing without
>>>> blocking Xe.
>>> Please also disable PSR and FBC with this or at least add a way for users to disable those features.
>>> Without frontbuffer tracker those two features will break in some cases.
>> FBC and PSR work completely as expected. I don't remove frontbuffer
>> tracking; I only remove the GEM parts.
>>
>> Explicit invalidation using pageflip or CPU rendering + DirtyFB continue
>> to work, as I validated on my laptop with FBC.
> Neither of which are relevant to the removal of the gem hooks.
>
> Like I already said ~10 times in the last meeting, we need a proper
> testcase. Here's a rough idea what it should do:
>
> prepare a batch with
> 1. spinner
> 2. something that clobbers the fb
>
> Then
> 1. grab reference crc
> 2. execbuffer
> 3. dirtyfb
> 4. wait long enough for fbc to recompress
> 5. terminate spinner
> 6. gem_sync
> 7. grab crc and compare with reference
>
> No idea what the current status of PSR+CRC is, so not sure
> whether we can actually test PSR or not.

This test doesn't make sense. DirtyFB should simply not return before 
execbuffer finishes.

~Maarten