drm: rcar-du: Add DRM_MODE_BLEND_PIXEL_NONE support

DRM_MODE_BLEND_PIXEL_NONE ignores an alpha channel.

Rcar-du driver supports only 3 formats with an alpha channel
(DRM_FORMAT_ARGB1555, DRM_FORMAT_ARGB8888 and DRM_FORMAT_ARGB4444). We
simply override the format passed to VSP1 for blending with the pixel
format without alpha channel.
Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Takanari Hayama <taki@igel.co.jp>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

drivers/gpu/drm/rcar-du/rcar_du_vsp.c

@@ -152,6 +152,7 @@ static void rcar_du_vsp_plane_setup(struct rcar_du_vsp_plane *plane)
 		.alpha = state->state.alpha >> 8,
 		.zpos = state->state.zpos,
 	};
+	u32 fourcc = state->format->fourcc;
 	unsigned int i;
 
 	cfg.src.left = state->state.src.x1 >> 16;
@@ -168,7 +169,23 @@ 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];
 
-	format = rcar_du_format_info(state->format->fourcc);
+	if (state->state.pixel_blend_mode == DRM_MODE_BLEND_PIXEL_NONE) {
+		switch (fourcc) {
+		case DRM_FORMAT_ARGB1555:
+			fourcc = DRM_FORMAT_XRGB1555;
+			break;
+
+		case DRM_FORMAT_ARGB4444:
+			fourcc = DRM_FORMAT_XRGB4444;
+			break;
+
+		case DRM_FORMAT_ARGB8888:
+			fourcc = DRM_FORMAT_XRGB8888;
+			break;
+		}
+	}
+
+	format = rcar_du_format_info(fourcc);
 	cfg.pixelformat = format->v4l2;
 
 	cfg.premult = state->state.pixel_blend_mode == DRM_MODE_BLEND_PREMULTI;
@@ -439,6 +456,7 @@ 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_PIXEL_NONE) |
 					BIT(DRM_MODE_BLEND_PREMULTI) |
 					BIT(DRM_MODE_BLEND_COVERAGE));