[PATCH v3 00/11] amd/display: Add GFX9+ modifier support.

[Alex Deucher]

I don't claim to be an expert with modifiers, but the changes all look
logical to me.  With VGH added to patch 10, this series is:
Reviewed-by: Alex Deucher <alexander.deucher at amd.com>


On Wed, Oct 21, 2020 at 7:31 PM Bas Nieuwenhuizen
<bas at basnieuwenhuizen.nl> wrote:
>
> This adds modifier support to the amdgpu kernel drivers for GFX9 and
> later GPUs. It has been tested on
>
> - VEGA10, RAVEN, NAVI14
> - weston, sway, X with xf86-video-amdgpu (i.e. legacy path still works)
>
> and includes some basic testing of the layout code.
>
> The main goal is to keep it somewhat simple and regression free, so
> on the display side this series only exposes what the current GPU
> can render to. While we could expose more I think that is more
> suitable for follow-up work as the benefit would be minimal and
> there are some more design discussion there to discuss that are
> orthogonal from the initial implementation.
>
> Similarly this series only exposes 32-bpp displayable DCC in the cases
> that radeonsi would use it and any extra capabilities here should be
> future work.
>
> I believe these are by far the most complicated modifiers we've seen
> up till now, mostly related to
>
> - GPU identification for cases where it matters wrt tiling.
> - Every generation having tiling layout changes
> - Compression settings.
>
> I believe the complexity is necessary as every layout should be different
> and all layouts should be the best in some situation (though not all
> combinations of GPU parameters will actually have an existing GPU).
>
> That said, on the render side the number of modifiers actually listed for
> a given GPU is ~10, and in the current implementation that is the same
> for the display side. (we could expose more actually differing layouts
> on the display side for cross-GPU compatibility, but I consider that
> out of scope for this initial work).
>
> This series can be found on
> https://github.com/BNieuwenhuizen/linux/tree/modifiers
>
> An userspace implementation in radeonsi can be found on
> https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6176
>
> which has been reviewed and is ready for submission once these kernel
> patches land.
>
> v2:
>
> Per suggestion from Daniel Vetter I added logic to get the tiling_flags at
> addfb2 time and convert them into modifiers for GFX9+.  Furthermore, the DCC
> constant econding modifers only get exposed on RAVEN2 and newer.
>
> v3:
>
> Fixed some typos, rebased and CCing more people to actually get a review.
>
> Bas Nieuwenhuizen (11):
>   drm/amd/display: Do not silently accept DCC for multiplane formats.
>   drm/amd: Init modifier field of helper fb.
>   drm/amd/display: Honor the offset for plane 0.
>   drm/fourcc:  Add AMD DRM modifiers.
>   drm/amd/display: Store tiling_flags in the framebuffer.
>   drm/amd/display: Convert tiling_flags to modifiers.
>   drm/amd/display: Refactor surface tiling setup.
>   drm/amd/display: Set DC options from modifiers.
>   drm/amd/display: Add formats for DCC with 2/3 planes.
>   drm/amd/display: Expose modifiers.
>   drm/amd/display: Clean up GFX9 tiling_flags path.
>
>  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c   | 169 +++-
>  drivers/gpu/drm/amd/amdgpu/amdgpu_fb.c        |   2 +-
>  drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h      |   3 +
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 754 ++++++++++++++----
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |   2 -
>  include/uapi/drm/drm_fourcc.h                 | 115 +++
>  6 files changed, 880 insertions(+), 165 deletions(-)
>
> --
> 2.28.0
>