linux-kernel - Re: [PATCH v9 0/4] drm: Add support for atomic async page-flip

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Message-ID: <cc10f6b0-e26e-4021-85ca-33cb1e58e937@amd.com>
Date:   Wed, 22 Nov 2023 15:23:46 -0500
From:   Hamza Mahfooz <hamza.mahfooz@....com>
To:     André Almeida <andrealmeid@...lia.com>,
        dri-devel@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Cc:     pierre-eric.pelloux-prayer@....com,
        'Marek Olšák' <maraeo@...il.com>,
        Michel Dänzer <michel.daenzer@...lbox.org>,
        intel-gfx@...ts.freedesktop.org,
        Randy Dunlap <rdunlap@...radead.org>,
        Pekka Paalanen <ppaalanen@...il.com>, kernel-dev@...lia.com,
        alexander.deucher@....com, christian.koenig@....com
Subject: Re: [PATCH v9 0/4] drm: Add support for atomic async page-flip

Hi André,
On 11/22/23 11:19, André Almeida wrote:
> Hi,
> 
> This work from me and Simon adds support for DRM_MODE_PAGE_FLIP_ASYNC through
> the atomic API. This feature is already available via the legacy API. The use
> case is to be able to present a new frame immediately (or as soon as
> possible), even if after missing a vblank. This might result in tearing, but
> it's useful when a high framerate is desired, such as for gaming.
> 
> Differently from earlier versions, this one refuses to flip if any prop changes
> for async flips. The idea is that the fast path of immediate page flips doesn't
> play well with modeset changes, so only the fb_id can be changed.
> 
> Tested with:
>   - Intel TigerLake-LP GT2
>   - AMD VanGogh

Have you had a chance to test this with VRR enabled? Since, I suspect
this series might break that feature.

> 
> Thanks,
> 	André
> 
> - User-space patch: https://github.com/Plagman/gamescope/pull/595
> - IGT tests: https://lore.kernel.org/all/20231110163811.24158-1-andrealmeid@igalia.com/
> 
> Changes from v8:
> - Dropped atomic_async_page_flip_not_supported, giving that current design works
> with any driver that support atomic and async at the same time.
> - Dropped the patch that disabled atomic_async_page_flip_not_supported for AMD.
> - Reordered commits
> v8: https://lore.kernel.org/all/20231025005318.293690-1-andrealmeid@igalia.com/
> 
> Changes from v7:
> - Only accept flips to primary planes. If a driver support flips in different
> planes, support will be added  later.
> v7: https://lore.kernel.org/dri-devel/20231017092837.32428-1-andrealmeid@igalia.com/
> 
> Changes from v6:
> - Dropped the exception to allow MODE_ID changes (Simon)
> - Clarify what happens when flipping with the same FB_ID (Pekka)
> 
> v6: https://lore.kernel.org/dri-devel/20230815185710.159779-1-andrealmeid@igalia.com/
> 
> Changes from v5:
> - Add note in the docs that not every redundant attribute will result in no-op,
>    some might cause oversynchronization issues.
> 
> v5: https://lore.kernel.org/dri-devel/20230707224059.305474-1-andrealmeid@igalia.com/
> 
> Changes from v4:
>   - Documentation rewrote by Pekka Paalanen
> 
> v4: https://lore.kernel.org/dri-devel/20230701020917.143394-1-andrealmeid@igalia.com/
> 
> Changes from v3:
>   - Add new patch to reject prop changes
>   - Add a documentation clarifying the KMS atomic state set
> 
> v3: https://lore.kernel.org/dri-devel/20220929184307.258331-1-contact@emersion.fr/
> 
> André Almeida (1):
>    drm: Refuse to async flip with atomic prop changes
> 
> Pekka Paalanen (1):
>    drm/doc: Define KMS atomic state set
> 
> Simon Ser (2):
>    drm: allow DRM_MODE_PAGE_FLIP_ASYNC for atomic commits
>    drm: introduce DRM_CAP_ATOMIC_ASYNC_PAGE_FLIP
> 
>   Documentation/gpu/drm-uapi.rst      | 47 ++++++++++++++++++
>   drivers/gpu/drm/drm_atomic_uapi.c   | 77 ++++++++++++++++++++++++++---
>   drivers/gpu/drm/drm_crtc_internal.h |  2 +-
>   drivers/gpu/drm/drm_ioctl.c         |  4 ++
>   drivers/gpu/drm/drm_mode_object.c   |  2 +-
>   include/uapi/drm/drm.h              | 10 +++-
>   include/uapi/drm/drm_mode.h         |  9 ++++
>   7 files changed, 142 insertions(+), 9 deletions(-)
> 
-- 
Hamza