Expose drm_plane_create_blend_mode_property() so Rust KMS drivers advertising alpha formats can declare how userspace should interpret the alpha channel.
Assisted-by: Claude:claude-opus-5 Signed-off-by: Mike Lothian <[email protected]> --- rust/kernel/drm/kms/plane.rs | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/rust/kernel/drm/kms/plane.rs b/rust/kernel/drm/kms/plane.rs index 62de8a1dad19..f148aed812f2 100644 --- a/rust/kernel/drm/kms/plane.rs +++ b/rust/kernel/drm/kms/plane.rs @@ -459,6 +459,22 @@ pub fn enable_fb_damage_clips(&self) { // registration is exactly what this helper is for. unsafe { bindings::drm_plane_enable_fb_damage_clips(self.as_raw()) } } + + /// Attaches the `pixel blend mode` property to this plane. + /// + /// `supported_modes` is a bitmask of `BIT(DRM_MODE_BLEND_*)`; `DRM_MODE_BLEND_PREMULTI` must + /// always be included. Any plane that advertises a pixel format with an alpha channel is + /// required to have this property -- `drm_mode_config_validate()` `WARN`s at registration + /// otherwise, because userspace has no way to know how the alpha will be interpreted. + /// + /// Call this during [`KmsDriver::create_objects`](crate::drm::kms::KmsDriver::create_objects), + /// before the device is registered. + pub fn create_blend_mode_property(&self, supported_modes: BlendModes) -> Result { + // SAFETY: `as_raw()` is a valid, not-yet-registered plane. + to_result(unsafe { + bindings::drm_plane_create_blend_mode_property(self.as_raw(), supported_modes.bits()) + }) + } } /// A trait implemented by any type that acts as a [`struct drm_plane`] interface.
