From 332ad707e38fb82dd998b4d0782c15579e5784f1 Mon Sep 17 00:00:00 2001 From: Melissa Wen Date: Wed, 26 Aug 2026 12:37:07 +0200 Subject: [PATCH] drm/amd/display: advertise PIXEL_NONE and PREMULTI blend mode for DCE MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit DCE can support PREMULTI and COVERAGE blend mode depending on its generation, however current driver implementation either doesn't expose more than primary and cursor plane, or doesn't program registers for any blend mode other than PIXEL_NONE. To fix the missing-blend-mode-prop warning according to current DCE plane caps, create blend mode property with PIXEL_NONE and PREMULTI for primary planes. As long as the background is black and there is no overlay plane, PIXEL_NONE and PREMULTI are equivalent, and PREMULTI has been the mandatory/default mode for years, so keep it to avoid regressions. Fixes: 860e748bddcc ("drm: ensure blend mode supported if pixel format with alpha exposed") Tested-by: Viktor Jägersküpper Tested-by: Dan Wheeler #v3 Reviewed-by: Timur Kristóf Reviewed-by: Alex Hung Reviewed-by: Leandro Ribeiro #v2 Signed-off-by: Melissa Wen Link: https://patch.msgid.link/20260826104143.39077-4-mwen@igalia.com --- .../amd/display/amdgpu_dm/amdgpu_dm_plane.c | 24 +++++++++++++------ 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c index 423e3cd7b9c9..e13b96358208 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c @@ -2208,14 +2208,24 @@ int amdgpu_dm_plane_init(struct amdgpu_display_manager *dm, if (res) return res; - /* TODO: Check which blend modes are supported in DCE-generation - * planes, i.e. DC_PLANE_TYPE_DCE_RGB/UNDERLAY and expose blend mode - * property accordingly. + /* Blend mode support varies on DCE generations according to HW caps + * and number of planes per CRTC. However, as current driver + * implementation only creates one primary and one cursor plane per + * CRTC for DCE (overlay is only created if + * DC_PLANE_TYPE_DCN_UNIVERSAL), the primary plane blend mode is + * ignored across DCE versions. Keep PREMULTI to avoid uAPI + * regressions: it was the default/mandatory mode for many years and, + * with no overlay plane, primary composes on top of a black + * background, where PREMULTI and PIXEL_NONE are equivalent. */ - if ((plane->type == DRM_PLANE_TYPE_OVERLAY || - plane->type == DRM_PLANE_TYPE_PRIMARY) && - plane_cap && plane_cap->per_pixel_alpha && - plane_cap->type == DC_PLANE_TYPE_DCN_UNIVERSAL) { + if (plane_cap && plane_cap->type != DC_PLANE_TYPE_DCN_UNIVERSAL) { + unsigned int blend_caps = BIT(DRM_MODE_BLEND_PIXEL_NONE) | + BIT(DRM_MODE_BLEND_PREMULTI); + + drm_plane_create_blend_mode_property(plane, blend_caps); + } else if ((plane->type == DRM_PLANE_TYPE_OVERLAY || + plane->type == DRM_PLANE_TYPE_PRIMARY) && + plane_cap && plane_cap->per_pixel_alpha) { unsigned int blend_caps = BIT(DRM_MODE_BLEND_PIXEL_NONE) | BIT(DRM_MODE_BLEND_PREMULTI) | BIT(DRM_MODE_BLEND_COVERAGE);