drm/msm/mdp5: add support for alpha/blend_mode properties

Hook alpha and pixel blend mode support to be exported as proper DRM
plane properties. This allows using this functionality from the
userspace.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20210525131316.3117809-5-dmitry.baryshkov@linaro.org
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c

@@ -91,6 +91,11 @@ static void mdp5_plane_install_properties(struct drm_plane *plane,
 	INSTALL_RANGE_PROPERTY(zpos, ZPOS, 1, 255, 1);
 
 	mdp5_plane_install_rotation_property(dev, plane);
+	drm_plane_create_alpha_property(plane);
+	drm_plane_create_blend_mode_property(plane,
+			BIT(DRM_MODE_BLEND_PIXEL_NONE) |
+			BIT(DRM_MODE_BLEND_PREMULTI) |
+			BIT(DRM_MODE_BLEND_COVERAGE));
 
 #undef INSTALL_RANGE_PROPERTY
 #undef INSTALL_ENUM_PROPERTY