[PATCH 2/2] drm/amd/display: Move PRIMARY plane zpos higher

[Pekka Paalanen]

On Fri, 15 Mar 2024 13:09:58 -0400
<sunpeng.li at amd.com> wrote:

> From: Leo Li <sunpeng.li at amd.com>
> 
> [Why]
> 
> Compositors have different ways of assigning surfaces to DRM planes for
> render offloading. It may decide between various strategies: overlay,
> underlay, or a mix of both
> 
> One way for compositors to implement the underlay strategy is to assign
> a higher zpos to the DRM_PRIMARY plane than the DRM_OVERLAY planes,
> effectively turning the DRM_OVERLAY plane into an underlay plane.
> 
> Today, amdgpu attaches an immutable zpos of 0 to the DRM_PRIMARY plane.
> This however, is an arbitrary restriction. DCN pipes are general
> purpose, and can be arranged in any z-order. To support compositors
> using this allocation scheme, we can set a non-zero immutable zpos for
> the PRIMARY, allowing the placement of OVERLAYS (mutable zpos range
> 0-254) beneath the PRIMARY.
> 
> [How]
> 
> Assign a zpos = #no of OVERLAY planes to the PRIMARY plane. Then, clean
> up any assumptions in the driver of PRIMARY plane having the lowest
> zpos.

This sounds good to me too. I suppose that means

Acked-by: Pekka Paalanen <pekka.paalanen at collabora.com>

for both patches. Or at least for their intentions. :-)


Thanks,
pq

> Signed-off-by: Leo Li <sunpeng.li at amd.com>
> ---
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 96 ++++++++++++++++++-
>  .../amd/display/amdgpu_dm/amdgpu_dm_plane.c   | 17 +++-
>  2 files changed, 104 insertions(+), 9 deletions(-)
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