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* [PATCH] drm/i915/display: expose blend mode on alpha-capable planes
@ 2026-07-15  5:42 Chaitanya Kumar Borah
  2026-07-15  6:22 ` ✓ CI.KUnit: success for " Patchwork
                   ` (4 more replies)
  0 siblings, 5 replies; 6+ messages in thread
From: Chaitanya Kumar Borah @ 2026-07-15  5:42 UTC (permalink / raw)
  To: intel-gfx, intel-xe
  Cc: Chaitanya Kumar Borah, Ville Syrjälä, Uma Shankar,
	Leandro Ribeiro

Since commit 860e748bddcc ("drm: ensure blend mode supported if pixel
format with alpha exposed"), drm_mode_config_validate() warns when a
plane exposes an alpha pixel format but not the "pixel blend mode"
property. The cursor (ARGB8888, all platforms) and the VLV/CHV primary
and sprite planes trip this.

Userspace has historically assumed premultiplied blending when the
property is not attached, so it is safe to assume that planes that
did not expose the property already blended with fixed pre-multiplied
alpha in hardware. Therefore, expose a "pixel blend mode" property
advertising only DRM_MODE_BLEND_PREMULTI to match that assumption and
silence the warning. The cursor call is unconditional; the primary and
sprite calls are gated to VLV/CHV, the only platforms whose format lists
include alpha formats.

Assisted-by: Claude:claude-opus-4-8
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Cc: Leandro Ribeiro <leandro.ribeiro@collabora.com>
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/16623
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
---
 drivers/gpu/drm/i915/display/i9xx_plane.c   | 4 ++++
 drivers/gpu/drm/i915/display/intel_cursor.c | 3 +++
 drivers/gpu/drm/i915/display/intel_sprite.c | 4 ++++
 3 files changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/i9xx_plane.c b/drivers/gpu/drm/i915/display/i9xx_plane.c
index 70734d32a409..490908f59141 100644
--- a/drivers/gpu/drm/i915/display/i9xx_plane.c
+++ b/drivers/gpu/drm/i915/display/i9xx_plane.c
@@ -1108,6 +1108,10 @@ intel_primary_plane_create(struct intel_display *display, enum pipe pipe)
 						   DRM_MODE_ROTATE_0,
 						   supported_rotations);
 
+	if (display->platform.valleyview || display->platform.cherryview)
+		drm_plane_create_blend_mode_property(&plane->base,
+						     BIT(DRM_MODE_BLEND_PREMULTI));
+
 	zpos = 0;
 	drm_plane_create_zpos_immutable_property(&plane->base, zpos);
 
diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index 88384dea868b..0673f16f6fd0 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -1078,6 +1078,9 @@ intel_cursor_plane_create(struct intel_display *display,
 
 	intel_cursor_add_size_hints_property(cursor);
 
+	drm_plane_create_blend_mode_property(&cursor->base,
+					     BIT(DRM_MODE_BLEND_PREMULTI));
+
 	zpos = DISPLAY_RUNTIME_INFO(display)->num_sprites[pipe] + 1;
 	drm_plane_create_zpos_immutable_property(&cursor->base, zpos);
 
diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c b/drivers/gpu/drm/i915/display/intel_sprite.c
index 6a65f92e8a03..3e38960bbbd8 100644
--- a/drivers/gpu/drm/i915/display/intel_sprite.c
+++ b/drivers/gpu/drm/i915/display/intel_sprite.c
@@ -1722,6 +1722,10 @@ intel_sprite_plane_create(struct intel_display *display,
 					  DRM_COLOR_YCBCR_BT709,
 					  DRM_COLOR_YCBCR_LIMITED_RANGE);
 
+	if (display->platform.valleyview || display->platform.cherryview)
+		drm_plane_create_blend_mode_property(&plane->base,
+						     BIT(DRM_MODE_BLEND_PREMULTI));
+
 	zpos = sprite + 1;
 	drm_plane_create_zpos_immutable_property(&plane->base, zpos);
 
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-07-15 12:01 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-07-15  5:42 [PATCH] drm/i915/display: expose blend mode on alpha-capable planes Chaitanya Kumar Borah
2026-07-15  6:22 ` ✓ CI.KUnit: success for " Patchwork
2026-07-15  7:08 ` ✓ Xe.CI.BAT: " Patchwork
2026-07-15  7:43 ` [PATCH] " Shankar, Uma
2026-07-15  8:19 ` ✓ Xe.CI.FULL: success for " Patchwork
2026-07-15 12:01 ` [PATCH] " Ville Syrjälä

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