Re: [PATCH 0/3] drm/amd/display: Fix HDMI RGB quantization updates

[Alex Hung <alex.hung@amd.com>]

Reviewed-by: Alex Hung <alex.hung@amd.com>

On 8/29/26 21:51, Satyajit Roy wrote:
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> 
> From: Satyajit Roy <sroy14@alum.utk.edu>
> 
> The Broadcast RGB implementation currently has three gaps in the AMD
> Display path:
> 
>    1. DM does not propagate the sink's RGB quantization-range
>       selectability into DC, so the HDMI AVI InfoFrame Q field remains at
>       its default value.
>    2. BT.2020 RGB output is always selected as full range, so an explicit
>       Limited setting has no effect in HDR modes using BT.2020 RGB.
>    3. A property-only range transition updates the output CSC but does not
>       rebuild and program the InfoFrame, leaving the sink with stale range
>       signaling.
> 
> Together these can make the transmitted pixel range and the range inferred
> by a television's automatic black-level setting disagree.
> 
> Patch 1 propagates the EDID QS capability. Patch 2 honors Limited for
> BT.2020 RGB and adds KUnit coverage for both BT.2020 connector colorspace
> values. Patch 3 rebuilds InfoFrames whenever output_color_space changes.
> 
> Validation performed on amd-staging-drm-next at the base commit below:
> 
>    - scripts/checkpatch.pl --strict: no errors, warnings, or checks
>    - x86_64 AMD Display KUnit configuration built with CONFIG_WERROR=y
>    - new EDID-capability and BT.2020 quantization KUnit cases compiled
> 
> Equivalent changes were also tested on an HDMI 2.1 television with a
> Valve Linux 7.2 kernel. The television's automatic black-level selection
> followed Full-to-Limited and Limited-to-Full transitions in SDR, HDR, and
> HDR with VRR active. No modeset or visible link blank was observed.
> 
> Satyajit Roy (3):
>    drm/amd/display: Propagate HDMI RGB quantization selectability
>    drm/amd/display: Honor Broadcast RGB for BT.2020 RGB output
>    drm/amd/display: Rebuild InfoFrames on output color space changes
> 
>   .../display/amdgpu_dm/amdgpu_dm_connector.c   | 10 +++--
>   .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  1 +
>   .../tests/amdgpu_dm_connector_test.c          | 37 +++++++++++++++++++
>   .../amdgpu_dm/tests/amdgpu_dm_helpers_test.c  |  2 +
>   drivers/gpu/drm/amd/display/dc/core/dc.c      |  3 ++
>   5 files changed, 50 insertions(+), 3 deletions(-)
> 
> 
> base-commit: 75a5e1b6b3661c3f946885d01eebeb6b031035ef
> --
> 2.51.1