A short description about the AMD color pipeline. Signed-off-by: Harry Wentland <harry.wentland@xxxxxxx> --- .../amd/display/amdgpu_dm/amdgpu_dm_color.c | 122 +++++++++++++++--- 1 file changed, 102 insertions(+), 20 deletions(-) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c index 3814f6fce4a2..8c5d91556462 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c @@ -33,6 +33,32 @@ /** * DOC: overview * + * We have three types of color management in the AMD display driver. + * 1. the legacy &drm_crtc DEGAMMA, CTM, and GAMMA properties + * 2. AMD driver private color management on &drm_plane and &drm_crtc + * 3. AMD plane color pipeline + * + * The CRTC properties are the original color management. When they were + * implemented per-plane color management was not a thing yet. Because + * of that we could get away with plumbing the DEGAMMA and CTM + * properties to pre-blending HW functions. This is incompatible with + * per-plane color management, such as via the AMD private properties or + * the new drm_plane color pipeline. The only compatible CRTC property + * with per-plane color management is the GAMMA property as it is + * applied post-blending. + * + * The AMD driver private color management properties are only exposed + * when the kernel is built explicitly with -DAMD_PRIVATE_COLOR. They + * are temporary building blocks on the path to full-fledged &drm_plane + * and &drm_crtc color pipelines and lay the driver's groundwork for the + * color pipelines. + * + * The AMD plane color pipeline describes AMD's &drm_colorops via the + * &drm_plane's COLOR_PIPELINE property. + * + * drm_crtc Properties + * ------------------- + * * The DC interface to HW gives us the following color management blocks * per pipe (surface): * @@ -43,33 +69,89 @@ * - Surface regamma LUT (normalized) * - Output CSC (normalized) * - * But these aren't a direct mapping to DRM color properties. The current DRM - * interface exposes CRTC degamma, CRTC CTM and CRTC regamma while our hardware - * is essentially giving: + * But these aren't a direct mapping to DRM color properties. The + * current DRM interface exposes CRTC degamma, CRTC CTM and CRTC regamma + * while our hardware is essentially giving: * * Plane CTM -> Plane degamma -> Plane CTM -> Plane regamma -> Plane CTM * - * The input gamma LUT block isn't really applicable here since it operates - * on the actual input data itself rather than the HW fp representation. The - * input and output CSC blocks are technically available to use as part of - * the DC interface but are typically used internally by DC for conversions - * between color spaces. These could be blended together with user - * adjustments in the future but for now these should remain untouched. + * The input gamma LUT block isn't really applicable here since it + * operates on the actual input data itself rather than the HW fp + * representation. The input and output CSC blocks are technically + * available to use as part of the DC interface but are typically used + * internally by DC for conversions between color spaces. These could be + * blended together with user adjustments in the future but for now + * these should remain untouched. * - * The pipe blending also happens after these blocks so we don't actually - * support any CRTC props with correct blending with multiple planes - but we - * can still support CRTC color management properties in DM in most single - * plane cases correctly with clever management of the DC interface in DM. + * The pipe blending also happens after these blocks so we don't + * actually support any CRTC props with correct blending with multiple + * planes - but we can still support CRTC color management properties in + * DM in most single plane cases correctly with clever management of the + * DC interface in DM. * - * As per DRM documentation, blocks should be in hardware bypass when their - * respective property is set to NULL. A linear DGM/RGM LUT should also - * considered as putting the respective block into bypass mode. + * As per DRM documentation, blocks should be in hardware bypass when + * their respective property is set to NULL. A linear DGM/RGM LUT should + * also considered as putting the respective block into bypass mode. * - * This means that the following - * configuration is assumed to be the default: + * This means that the following configuration is assumed to be the + * default: + * + * Plane DGM Bypass -> Plane CTM Bypass -> Plane RGM Bypass -> ... CRTC + * DGM Bypass -> CRTC CTM Bypass -> CRTC RGM Bypass + * + * AMD Private Color Management on drm_plane + * ----------------------------------------- + * + * The AMD private color management properties on a &drm_plane are: + * + * - AMD_PLANE_DEGAMMA_LUT + * - AMD_PLANE_DEGAMMA_LUT_SIZE + * - AMD_PLANE_DEGAMMA_TF + * - AMD_PLANE_HDR_MULT + * - AMD_PLANE_CTM + * - AMD_PLANE_SHAPER_LUT + * - AMD_PLANE_SHAPER_LUT_SIZE + * - AMD_PLANE_SHAPER_TF + * - AMD_PLANE_LUT3D + * - AMD_PLANE_LUT3D_SIZE + * - AMD_PLANE_BLEND_LUT + * - AMD_PLANE_BLEND_LUT_SIZE + * - AMD_PLANE_BLEND_TF + * + * The AMD private color management property on a &drm_crtc is: + * + * - AMD_CRTC_REGAMMA_TF + * + * Use of these properties is discouraged. + * + * AMD plane color pipeline + * ------------------------ + * + * The AMD &drm_plane color pipeline is advertised for DCN generations + * 3.0 and newer. It exposes these elements in this order: + * + * 1. 1D curve colorop + * 2. Multiplier + * 3. 3x4 CTM + * 4. 1D curve colorop + * 5. 1D LUT + * 6. 3D LUT + * 7. 1D curve colorop + * 8. 1D LUT + * + * The multiplier (#2) is a simple multiplier that is applied to all + * channels. + * + * The 3x4 CTM (#3) is a simple 3x4 matrix. + * + * #1, and #7 are non-linear to linear curves. #4 is a linear to + * non-linear curve. They support sRGB, PQ, and BT.709/BT.2020 EOTFs or + * their inverse. + * + * The 1D LUTs (#5 and #8) are plain 4096 entry LUTs. + * + * The 3DLUT (#6) is a tetrahedrally interpolated 17 cube LUT. * - * Plane DGM Bypass -> Plane CTM Bypass -> Plane RGM Bypass -> ... - * CRTC DGM Bypass -> CRTC CTM Bypass -> CRTC RGM Bypass */ #define MAX_DRM_LUT_VALUE 0xFFFF -- 2.46.2
