[PATCH 0/2] drm/atomic: Allow drivers to write their own plane check for async

[Joshua Ashton]

On 1/16/24 13:35, André Almeida wrote:
> + Joshua
> 
> Em 16/01/2024 10:14, Pekka Paalanen escreveu:
>> On Tue, 16 Jan 2024 08:50:59 -0300
>> André Almeida <andrealmeid at igalia.com> wrote:
>>
>>> Hi Pekka,
>>>
>>> Em 16/01/2024 06:45, Pekka Paalanen escreveu:
>>>> On Tue, 16 Jan 2024 01:51:57 -0300
>>>> André Almeida <andrealmeid at igalia.com> wrote:
>>>>> Hi,
>>>>>
>>>>> AMD hardware can do more on the async flip path than just the 
>>>>> primary plane, so
>>>>> to lift up the current restrictions, this patchset allows drivers 
>>>>> to write their
>>>>> own check for planes for async flips.
>>>>
>>>> Hi,
>>>>
>>>> what's the userspace story for this, how could userspace know it 
>>>> could do more?
>>>> What kind of userspace would take advantage of this and in what 
>>>> situations?
>>>>
>>>> Or is this not meant for generic userspace?
>>>
>>> Sorry, I forgot to document this. So the idea is that userspace will
>>> query what they can do here with DRM_MODE_ATOMIC_TEST_ONLY calls,
>>> instead of having capabilities for each prop.
>>
>> That's the theory, but do you have a practical example?
>>
>> What other planes and props would one want change in some specific use
>> case?
>>
>> Is it just "all or nothing", or would there be room to choose and pick
>> which props you change and which you don't based on what the driver
>> supports? If the latter, then relying on TEST_ONLY might be yet another
>> combinatorial explosion to iterate through.
>>
> 
> That's a good question, maybe Simon, Xaver or Joshua can share how they 
> were planning to use this on Gamescope or Kwin.

Gamescope would just like to do async updates for overlay planes eg. the 
perf overlay etc.

That way we can avoid having to do sync commits when we have the perf 
overlay up.

It'd also be nice to do always do some form of async updates for VRR for 
the overlay planes.

- Joshie 🐸✨

> 
>>
>> Thanks,
>> pq
>>
>>>>> I'm not sure if adding something new to drm_plane_funcs is the 
>>>>> right way to do,
>>>>> because if we want to expand the other object types (crtc, 
>>>>> connector) we would
>>>>> need to add their own drm_XXX_funcs, so feedbacks are welcome!
>>>>>
>>>>>     André
>>>>>
>>>>> André Almeida (2):
>>>>>     drm/atomic: Allow drivers to write their own plane check for async
>>>>>       flips
>>>>>     drm/amdgpu: Implement check_async_props for planes
>>>>>
>>>>>    .../amd/display/amdgpu_dm/amdgpu_dm_plane.c   | 30 +++++++++
>>>>>    drivers/gpu/drm/drm_atomic_uapi.c             | 62 
>>>>> ++++++++++++++-----
>>>>>    include/drm/drm_atomic_uapi.h                 | 12 ++++
>>>>>    include/drm/drm_plane.h                       |  5 ++
>>>>>    4 files changed, 92 insertions(+), 17 deletions(-)
>>