[PATCH V11 00/47] Color Pipeline API w/ VKMS
Sebastian Wick
sebastian.wick at redhat.com
Wed Aug 20 19:43:16 UTC 2025
With the small improvements, the core drm parts are
Reviewed-by: Sebastian Wick <sebastian.wick at redhat.com>
On Fri Aug 15, 2025 at 5:49 AM CEST, Alex Hung wrote:
> This is an RFC set for a color pipeline API, along with implementations
> in VKMS and amdgpu. It is tested with a set of IGT tests that can be
> found at [1]. The IGT tests run a pixel-by-pixel comparison with an
> allowable delta variation as the goal for these transformations is
> perceptual correctness, not complete pixel accuracy.
>
> v5 of this patchset fleshed out documentation for colorops and the
> various defines that are being introduced.
>
> v6 addresses a few comments from various reviewers.
>
> v7 simplifies 3D LUT and addresses more comments from various reviewers.
>
> v8 fixes typo and errors and address comments from reviewers.
>
> v9 refactors cleanup functions, fixes typo and errors, and addresses
> comments from reviewers.
>
> v10 add 32BIT RGB (drm_color_lut_32) to 1D & 3D LUTs, addresses comments
> from reviewers, and fixes typo and errors.
>
> v11 change names from *_lut_32_* to *_lut32_* and fix RGB 32bit
> extractions.
>
> VKMS supports two named transfer function colorops and two matrix
> colorops.
>
> Amdgpu advertises the following pipeline for GPUs with DCN 3 or newer:
>
> 1. 1D Curve EOTF
> 2. 3x4 CTM
> 3. Multiplier
> 4. 1D Curve Inverse EOTF
> 5. 1D LUT
> 6. 3D LUT
> 7. 1D Curve EOTF
> 8. 1D LUT
>
> The supported curves for the 1D Curve type are:
> - sRGB EOTF and its inverse
> - PQ EOTF, scaled to [0.0, 125.0] and its inverse
> - BT.2020/BT.709 OETF and its inverse
>
> Note that the 1st and 5th colorops take the EOTF or Inverse
> OETF while the 3rd colorop takes the Inverse EOTF or OETF.
>
> The 3D LUT is a 17^3 tetrahedrally interpolated LUT but the mechanism
> exists for other drivers to describe their own 3D LUT capability.
>
> This mirrors the color pipeline used by gamescope and presented by
> Melissa Wen, with the exception of the DEGAM LUT, which is not currently
> used. See [1]
> https://indico.freedesktop.org/event/4/contributions/186/attachments/138/218/xdc2023-TheRainbowTreasureMap-MelissaWen.pdf
>
> At this point we're hoping to see gamescope, kwin and weston implementations
> take shape. The existing pipeline should be enough to satisfy the
> gamescope use-cases on the drm_plane.
>
> In order to support YUV we'll need to add COLOR_ENCODING and COLOR_RANGE
> support to the color pipeline. I have sketched these out already but
> don't have it all hooked up yet. This should not hinder adoption of this
> API for gaming use-cases.
>
> We'll also want to advertise IN_FORMATS on a color pipeline as some
> color pipelines won't be able to work for all IN_FORMATS on a plane.
> Again, I have a sketch but no full implementation yet. This is not
> currently required by the AMD color pipeline and could be added after
> the merge of this set.
>
> VKMS patches could still be improved in a few ways, though the
> payoff might be limited and I would rather focus on other work
> at the moment. The most obvious thing to improve would be to
> eliminate the hard-coded LUTs for identity, and sRGB, and replace
> them with fixed-point math instead.
>
> There are plenty of things that I would like to see, but they could
> be added after the merge of this patchset:
> - COLOR_ENCODING and COLOR_RANGE
> - IN_FORMATS for a color pipeline
> - Is it possible to support HW which can't bypass entire pipeline?
> - Can we do a LOAD / COMMIT model for LUTs (and other properties)?
> - read-only scaling colorop which defines scaling taps and position
> - named matrices, for things like converting YUV to RGB
> - Add custom LUT colorops to VKMS
>
> IGT tests can be found at [1] or on the igt-dev mailing list. There
> have been no updates since v5 and rebase on latest main is straight-
> forward.
>
> A kernel branch can be found at [2].
>
> [1] https://gitlab.freedesktop.org/alex.hung/igt-gpu-tools/-/tree/amd-color-pipeline-v10
> [2] https://gitlab.freedesktop.org/alex.hung/linux/-/tree/amd-color-pipeline-v11
>
> v11:
> - Refactor vkms_color_test_lerp() to parametized tests (Maíra Canal)
> - Sort include file alphabetically (Maíra Canal)
> - Skip color_encoding/range_property in drm_mode_object_get_properties
> when plane_color_pipeline is present (Harry Wentland)
> - destroy function takes drm_device *dev instead of drm_plane *plane
> (Nícolas Prado)
> - Fix undefined errors by EXPORT_SYMBOL symbols (kernel test robot)
> - Fix comments to "2nd op 3x4 matrix" (Nícolas Prado)
> - Update outdated "drm_rect_test_suite" to "drm_fixp_test_suite" (Maíra
> Canal)
> - Update outdated MODULE_LICENSE to Dual MIT/GPL (Maíra Canal)
> - Create color pipeline on supported hardware only (Melissa Wen)
> - Update names from *_lut_32_* to *_lut32_* (Simon Ser)
> - Include help function drm_color_lut32_extract (Uma Shankar)
> - Remove redundant is_legacy from __drm_lut_32_to_dc_gamma (kernel bot)
> - Fix RGB 32bit extraction from LUT (Xaver Hugl)
> - Handle errors in __set_colorop_3dlut (Nícolas Prado)
> - Merged enable condition for drm_crtc_enable_color_mgmt (Melissa Wen)
>
> v10:
> - remove duplicated "is useful" in comments (Melissa Wen)
> - guard "dm_plane_init_colorops" function when !AMD_PRIVATE_COLOR (Melissa Wen)
> - Replace DRM_ERROR by drm_err
> - Creaet color pipeline when >= DCN_VERSION_3_0 (Melissa Wen)
> - Relocate amdgpu_dm_supported_*_tfs check (Melissa Wen)
> - Support 32BIT RGB for 1D LUTs (Uma Shankar)
> - Support 32BIT RGB for 3D LUTs (Harry Wentland)
> - Fix typo mutliplier to multiplier in subject (Melissa Wen)
> - 1D & 3D LUTs are no longer immutable ((Xaver Hugl)
> - Fix 3D LUT kernel doc (Leandro Ribeiro)
> - Check dpp.hw_3d_lut before creating shaper tf/lut and 3dlut colorops (Melissa Wen)
> - Disable CRTC degamma when color pipeline is enabled (Melissa Wen)
>
> v9:
> - Update RFC documents for 3DLUT and fallback behaviours (Simon Ser)
> - Specify colorop function names by _plane_ (Chaitanya Kumar Borah)
> - Remove redundant comments (Simon Ser)
> - Fix typo in commit description (Shengyu Qu)
> - Move destroy and cleanup functions earlier (Simon Ser)
> - Move DRM_COLOROP_1D_CURVE_BT2020_* from middle to end (Simon Ser)
> - Chagne "bool allow_bypass" to "uint32_t flags" for better extensibility (Simon Ser)
> - Return a value in __set_dm_plane_colorop_3dlut
>
> v8:
> - Change VKMS config names (Louis Chauvet)
> - Remove deprecated function "drm_atomic_get_existing_colorop_state" (Louis Chauvet)
> - Remove null check in drm_colorop_set_next_property (Simon Ser)
> - Remove MAX_COLOR_PIPELINES in drm (Simon Ser)
> - Update kernel docs and documents for DRM_COLOROP_3D_LUT (Simon Ser)
> - Add comments for dmr_color_lut (Louis Chauvet)
> - Fix typos and replace DRM_ERROR and DRM_WARN_ONCE by drm_err drm_WARN_ONCE (Louis Chauvet)
> - Fix incorrect conditions in __set_colorop_in_tf_1d_curve (Leo Li)
> - Add DRM_MODE_PROP_ATOMIC to drm_property_create_range (Simon Ser)
> - Change "1D Curve Custom LUT" to "1D LUT" (Simon Ser)
> - Return error when __set_output_tf fails (Leo Li)
> - Return -EINVAL when drm_color_ctm_3x4's size mismatches (Leo Li)
> - Set initialized to 0 and return when drm_lut3d_size is 0 (Harry Wentland)
> - Rework tf->type = TF_TYPE_BYPASS for shaper (Harry Wentland & Leo Li)
>
> v7:
> - Simplify 3D LUT by removing lut_3d_modes and update doc accordingly (Simon Ser)
> - Add destroy / cleanup functions when color pipeline initialization
> fails (Louis Chauvet)
> - Fix checkpatch errors and warning (spaces, long lines, {}, and etc)
> - Change lut's size from drm_colorop_state->size to drm_colorop->lut_size
> and from size_property to lut_size_property
> - Update some kernel updates and commit messagesa (Louis Chauvet)
> - Squash "drm/colorop: Add atomic state print for drm_colorop" and
> "drm/colorop: Add NEXT to colorop state print" (Simon Ser)
> - Add missing MODULE_DESCRIPTION (Jeff Johnson)
>
> v6:
> - Eliminate need to include test as .c file (Louis Chauvet)
> - some doc updates
> - cleanup if colorop alloc or init fails in VKMS and amdgpu (Louis Chauvet)
> - couple other small improvements in VKMS, such as rounding (Louis Chauvet)
> - take ref for DATA blob in duplicate_state func & fix refcount issues (Xaver Hugl)
>
> v5:
> - amdgpu 3D LUT
> - Don't require BYPASS
> - update RFC docs and add to TOC tree
> - add drm_colorop and COLOR_PIPELINE kernel docs (non-RFC)
> - add amdgpu color pipeline doc
> - define SIZE property similar to drm_crtc's GAMMA_SIZE
> - various minor fixes and cleanups
>
> v4:
> - Add amdgpu color pipeline (WIP)
> - Don't block setting of deprecated properties, instead pass client cap
> to atomic check so drivers can ignore these props
> - Drop IOCTL definitions (Pekka)
> - Use enum property for colorop TYPE (Pekka)
> - A few cleanups to the docs (Pekka)
> - Rework the TYPE enum to name relation to avoid code duplication (Pekka)
> - Add missing function declarations (Chaitanya Kumar Borah)
> - Allow setting of NEXT property to NULL in _set_ function (Chaitanya Kumar Borah)
> - Add helper for creation of pipeline drm_plane property (Pekka)
> - Always create Bypass pipeline (Pekka)
> - A bunch of changes to VKMS kunit tests (Pekka)
> - Fix index in CTM doc (Pekka)
>
> v3:
> - Abandon IOCTLs and discover colorops as clients iterate the pipeline
> - Remove need for libdrm
> - Add color_pipeline client cap and make mutually exclusive with
> COLOR_RANGE and COLOR_ENCODING properties
> - add CTM colorop to VKMS
> - Use include way for kunit testing static functions (Arthur)
> - Make TYPE a range property
> - Move enum drm_colorop_type to uapi header
> - and a bunch of smaller bits that are highlighted in the relevant commit
> description
>
> v2:
> - Rebased on drm-misc-next
> - Introduce a VKMS Kunit so we can test LUT functionality in vkms_composer
> - Incorporate feedback in color_pipeline.rst doc
> - Add support for sRGB inverse EOTF
> - Add 2nd enumerated TF colorop to VKMS
> - Fix LUTs and some issues with applying LUTs in VKMS
>
> Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
> Cc: Pekka Paalanen <pekka.paalanen at collabora.com>
> Cc: Simon Ser <contact at emersion.fr>
> Cc: Harry Wentland <harry.wentland at amd.com>
> Cc: Melissa Wen <mwen at igalia.com>
> Cc: Jonas Ådahl <jadahl at redhat.com>
> Cc: Sebastian Wick <sebastian.wick at redhat.com>
> Cc: Shashank Sharma <shashank.sharma at amd.com>
> Cc: Alexander Goins <agoins at nvidia.com>
> Cc: Joshua Ashton <joshua at froggi.es>
> Cc: Michel Dänzer <mdaenzer at redhat.com>
> Cc: Aleix Pol <aleixpol at kde.org>
> Cc: Xaver Hugl <xaver.hugl at gmail.com>
> Cc: Victoria Brekenfeld <victoria at system76.com>
> Cc: Sima <daniel at ffwll.ch>
> Cc: Uma Shankar <uma.shankar at intel.com>
> Cc: Naseer Ahmed <quic_naseer at quicinc.com>
> Cc: Christopher Braga <quic_cbraga at quicinc.com>
> Cc: Abhinav Kumar <quic_abhinavk at quicinc.com>
> Cc: Arthur Grillo <arthurgrillo at riseup.net>
> Cc: Hector Martin <marcan at marcan.st>
> Cc: Liviu Dudau <Liviu.Dudau at arm.com>
> Cc: Sasha McIntosh <sashamcintosh at google.com>
> Cc: Chaitanya Kumar Borah <chaitanya.kumar.borah at intel.com>
>
> Alex Hung (16):
> drm/colorop: Add destroy functions for color pipeline
> drm/colorop: define a new macro for_each_new_colorop_in_state
> drm/amd/display: Skip color pipeline initialization for cursor plane
> drm/amd/display: Add support for sRGB EOTF in DEGAM block
> drm/amd/display: Add support for sRGB Inverse EOTF in SHAPER block
> drm/amd/display: Add support for sRGB EOTF in BLND block
> drm/colorop: Add 1D Curve Custom LUT type
> drm/amd/display: add shaper and blend colorops for 1D Curve Custom LUT
> drm/amd/display: add 3x4 matrix colorop
> drm/colorop: Add multiplier type
> drm/amd/display: add multiplier colorop
> drm/amd/display: Swap matrix and multiplier
> drm/colorop: Add 3D LUT support to color pipeline
> drm/amd/display: add 3D LUT colorop
> drm/amd/display: Ensure 3D LUT for color pipeline
> drm/amd/display: Disable CRTC degamma when color pipeline is enabled
>
> Chaitanya Kumar Borah (1):
> drm: Add helper to extract lut from struct drm_color_lut32
>
> Harry Wentland (29):
> drm: Add helper for conversion from signed-magnitude
> drm/vkms: Add kunit tests for VKMS LUT handling
> drm/doc/rfc: Describe why prescriptive color pipeline is needed
> drm/colorop: Introduce new drm_colorop mode object
> drm/colorop: Add TYPE property
> drm/colorop: Add 1D Curve subtype
> drm/colorop: Add BYPASS property
> drm/colorop: Add NEXT property
> drm/colorop: Add atomic state print for drm_colorop
> drm/plane: Add COLOR PIPELINE property
> drm/colorop: Introduce DRM_CLIENT_CAP_PLANE_COLOR_PIPELINE
> Documentation/gpu: document drm_colorop
> drm/vkms: Add enumerated 1D curve colorop
> drm/vkms: Add kunit tests for linear and sRGB LUTs
> drm/colorop: Add 3x4 CTM type
> drm/vkms: Use s32 for internal color pipeline precision
> drm/vkms: add 3x4 matrix in color pipeline
> drm/tests: Add a few tests around drm_fixed.h
> drm/vkms: Add tests for CTM handling
> drm/colorop: pass plane_color_pipeline client cap to atomic check
> drm/amd/display: Ignore deprecated props when plane_color_pipeline set
> drm/amd/display: Add bypass COLOR PIPELINE
> drm/colorop: Add PQ 125 EOTF and its inverse
> drm/amd/display: Enable support for PQ 125 EOTF and Inverse
> drm/colorop: add BT2020/BT709 OETF and Inverse OETF
> drm/amd/display: Add support for BT.709 and BT.2020 TFs
> drm/colorop: Define LUT_1D interpolation
> drm/colorop: allow non-bypass colorops
> drm/amd/display: Add AMD color pipeline doc
>
> Uma Shankar (1):
> drm: Add Enhanced LUT precision structure
>
> Documentation/gpu/drm-kms.rst | 15 +
> Documentation/gpu/rfc/color_pipeline.rst | 378 ++++++++
> Documentation/gpu/rfc/index.rst | 3 +
> drivers/gpu/drm/Makefile | 1 +
> .../gpu/drm/amd/display/amdgpu_dm/Makefile | 3 +-
> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 +
> .../amd/display/amdgpu_dm/amdgpu_dm_color.c | 765 ++++++++++++++++-
> .../amd/display/amdgpu_dm/amdgpu_dm_colorop.c | 205 +++++
> .../amd/display/amdgpu_dm/amdgpu_dm_colorop.h | 36 +
> .../amd/display/amdgpu_dm/amdgpu_dm_crtc.c | 26 +-
> .../amd/display/amdgpu_dm/amdgpu_dm_plane.c | 39 +
> drivers/gpu/drm/drm_atomic.c | 170 +++-
> drivers/gpu/drm/drm_atomic_helper.c | 12 +
> drivers/gpu/drm/drm_atomic_state_helper.c | 5 +
> drivers/gpu/drm/drm_atomic_uapi.c | 159 ++++
> drivers/gpu/drm/drm_color_mgmt.c | 43 +
> drivers/gpu/drm/drm_colorop.c | 597 +++++++++++++
> drivers/gpu/drm/drm_connector.c | 1 +
> drivers/gpu/drm/drm_crtc_internal.h | 1 +
> drivers/gpu/drm/drm_ioctl.c | 7 +
> drivers/gpu/drm/drm_mode_config.c | 7 +
> drivers/gpu/drm/drm_mode_object.c | 18 +
> drivers/gpu/drm/drm_plane.c | 59 ++
> drivers/gpu/drm/tests/Makefile | 3 +-
> drivers/gpu/drm/tests/drm_fixp_test.c | 71 ++
> drivers/gpu/drm/vkms/Makefile | 4 +-
> drivers/gpu/drm/vkms/tests/Makefile | 2 +-
> drivers/gpu/drm/vkms/tests/vkms_color_test.c | 417 +++++++++
> drivers/gpu/drm/vkms/vkms_colorop.c | 115 +++
> drivers/gpu/drm/vkms/vkms_composer.c | 134 ++-
> drivers/gpu/drm/vkms/vkms_composer.h | 27 +
> drivers/gpu/drm/vkms/vkms_drv.h | 7 +
> drivers/gpu/drm/vkms/vkms_luts.c | 811 ++++++++++++++++++
> drivers/gpu/drm/vkms/vkms_luts.h | 12 +
> drivers/gpu/drm/vkms/vkms_plane.c | 2 +
> include/drm/drm_atomic.h | 111 +++
> include/drm/drm_atomic_uapi.h | 3 +
> include/drm/drm_color_mgmt.h | 29 +
> include/drm/drm_colorop.h | 442 ++++++++++
> include/drm/drm_file.h | 7 +
> include/drm/drm_fixed.h | 18 +
> include/drm/drm_mode_config.h | 18 +
> include/drm/drm_plane.h | 19 +
> include/uapi/drm/amdgpu_drm.h | 9 -
> include/uapi/drm/drm.h | 15 +
> include/uapi/drm/drm_mode.h | 134 +++
> 46 files changed, 4900 insertions(+), 64 deletions(-)
> create mode 100644 Documentation/gpu/rfc/color_pipeline.rst
> create mode 100644 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_colorop.c
> create mode 100644 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_colorop.h
> create mode 100644 drivers/gpu/drm/drm_colorop.c
> create mode 100644 drivers/gpu/drm/tests/drm_fixp_test.c
> create mode 100644 drivers/gpu/drm/vkms/tests/vkms_color_test.c
> create mode 100644 drivers/gpu/drm/vkms/vkms_colorop.c
> create mode 100644 drivers/gpu/drm/vkms/vkms_composer.h
> create mode 100644 drivers/gpu/drm/vkms/vkms_luts.c
> create mode 100644 drivers/gpu/drm/vkms/vkms_luts.h
> create mode 100644 include/drm/drm_colorop.h
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