[PATCH v2 2/3] drm: rcar-du: Add DRM_MODE_BLEND_PREMULTI support

[Takanari Hayama]

R-Car DU driver implicitly supports DRM_MODE_BLEND_COVERAGE only.
This adds a support for DRM_MODE_BLEND_PREMULTI. As a consequence,
DRM_MODE_BLEND_PREMULTI becomes the default. If DRM_MODE_BLEND_COVERAGE
is desired, it should be set explicitly.

This behavior comes from how DRM blend mode is supported.
drm_plane_create_blend_mode_property() creates the blend mode property
with the default value of DRM_MODE_BLEND_PREMULTI. This default value
cannot be modified from the atomic driver.

Signed-off-by: Takanari Hayama <taki at igel.co.jp>
---
 drivers/gpu/drm/rcar-du/rcar_du_vsp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
index 8eb9b2b097ae..b9580fcfec7a 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
@@ -167,6 +167,8 @@ static void rcar_du_vsp_plane_setup(struct rcar_du_vsp_plane *plane)
 		cfg.mem[i] = sg_dma_address(state->sg_tables[i].sgl)
 			   + fb->offsets[i];
 
+	cfg.premult = (state->state.pixel_blend_mode == DRM_MODE_BLEND_PREMULTI);
+
 	format = rcar_du_format_info(state->format->fourcc);
 	cfg.pixelformat = format->v4l2;
 
@@ -444,6 +446,10 @@ int rcar_du_vsp_init(struct rcar_du_vsp *vsp, struct device_node *np,
 						       num_planes - 1);
 		}
 
+		drm_plane_create_blend_mode_property(&plane->plane,
+					BIT(DRM_MODE_BLEND_PREMULTI) |
+					BIT(DRM_MODE_BLEND_COVERAGE));
+
 		vsp->num_planes++;
 	}
 
-- 
2.25.1