From f2e64f450c1665732505dae8ee34b399da5a5100 Mon Sep 17 00:00:00 2001 From: Qinyun Tan Date: Tue, 1 Sep 2026 16:32:33 +0800 Subject: [PATCH] drm/virtio: create blend mode property on cursor plane 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 virtio-gpu cursor plane (HOST_ARGB8888) trips this. The virtio-gpu specification does not define the cursor alpha semantics. The host forwards the cursor pixels verbatim to its display frontends, and the remote cursor protocols among them (SPICE alpha cursors, the VNC "Cursor With Alpha" encoding) both define pre-multiplied alpha, matching what userspace has always assumed when the property is not attached. Expose a "pixel blend mode" property advertising only DRM_MODE_BLEND_PREMULTI to make these semantics explicit and silence the warning. The primary plane only exposes HOST_XRGB8888, so the call is gated to the cursor. No functional change. Fixes: 860e748bddcc ("drm: ensure blend mode supported if pixel format with alpha exposed") Reviewed-by: Thomas Zimmermann Signed-off-by: Qinyun Tan Signed-off-by: Thomas Zimmermann Link: https://patch.msgid.link/20260901083234.1828755-4-qinyuntan@linux.alibaba.com --- drivers/gpu/drm/virtio/virtgpu_plane.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c index 1d1b27ece62a..640815af4098 100644 --- a/drivers/gpu/drm/virtio/virtgpu_plane.c +++ b/drivers/gpu/drm/virtio/virtgpu_plane.c @@ -24,6 +24,7 @@ */ #include +#include #include #include #include @@ -609,6 +610,9 @@ struct drm_plane *virtio_gpu_plane_init(struct virtio_gpu_device *vgdev, if (type == DRM_PLANE_TYPE_PRIMARY) drm_plane_enable_fb_damage_clips(plane); + else if (type == DRM_PLANE_TYPE_CURSOR) + drm_plane_create_blend_mode_property(plane, + BIT(DRM_MODE_BLEND_PREMULTI)); return plane; }