linux-kernel - [PATCH v3] drm/edid DSC pass-through timing support

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Message-Id: <20230226141051.21767-1-iam@lach.pw>
Date:   Sun, 26 Feb 2023 15:10:49 +0100
From:   Yaroslav Bolyukin <iam@...h.pw>
To:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Cc:     Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Jani Nikula <jani.nikula@...el.com>,
        Yaroslav Bolyukin <iam@...h.pw>
Subject: [PATCH v3] drm/edid DSC pass-through timing support

VESA DisplayID spec allows the device to force its DSC bits per pixel
value.

For example, the HTC Vive Pro 2 VR headset uses this value in
high-resolution modes (3680x1836@...120, 4896x2448@...120), and when the
kernel doesn't respect this parameter, the garbage is displayed on HMD
instead.

I am unaware of any other hardware using this value; however, multiple
users have tested this patch on the Vive Pro 2, and it is known to work and
not break anything else.

Regarding driver support - I have looked at amdgpu and Nvidia's
open-gpu-kernel-modules, and both seem to have some indication for this
value; however, in Linux, it is unused in both. 

Amdgpu integration was trivial, so I implemented it in the second patch;
other kernel drivers still need the support of this value, and I don't have
the necessary hardware to implement and test the handling of this value on
them.

BR,
Yaroslav

Yaroslav Bolyukin (2):
  drm/edid: parse DRM VESA dsc bpp target
  drm/amd: use fixed dsc bits-per-pixel from edid

 .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  2 +
 .../gpu/drm/amd/display/dc/core/dc_stream.c   |  2 +
 drivers/gpu/drm/amd/display/dc/dc_types.h     |  3 ++
 drivers/gpu/drm/drm_edid.c                    | 42 ++++++++++++-------
 include/drm/drm_connector.h                   |  6 +++
 include/drm/drm_displayid.h                   |  4 ++
 6 files changed, 45 insertions(+), 14 deletions(-)

base-commit: a48bba98380cb0b43dcd01d276c7efc282e3c33f
--
2.39.1