gpu: ipu-v3: add support for separate alpha channels

The IPUv3 can read 8-bit alpha values from a separate IDMAC channel driven
by the Alpha Transparency Controller (ATC) for the graphics IDMAC channels.
This allows to reduce memory bandwidth via a conditional read mechanism or
to support planar YUV formats with alpha transparency.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/ipu-v3/ipu-common.c

@@ -83,6 +83,12 @@ enum ipu_color_space ipu_drm_fourcc_to_colorspace(u32 drm_fourcc)
 	case DRM_FORMAT_ABGR8888:
 	case DRM_FORMAT_RGBA8888:
 	case DRM_FORMAT_BGRA8888:
+	case DRM_FORMAT_RGB565_A8:
+	case DRM_FORMAT_BGR565_A8:
+	case DRM_FORMAT_RGB888_A8:
+	case DRM_FORMAT_BGR888_A8:
+	case DRM_FORMAT_RGBX8888_A8:
+	case DRM_FORMAT_BGRX8888_A8:
 		return IPUV3_COLORSPACE_RGB;
 	case DRM_FORMAT_YUYV:
 	case DRM_FORMAT_UYVY: