[PATCH 6/7] drm: add RGB formats with separate alpha plane

[Philipp Zabel]

Some hardware can read the alpha components separately and then
conditionally fetch color components only for non-zero alpha values.
This patch adds fourcc definitions for two-plane RGB formats with an
8-bit alpha channel on a second plane.

Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
---
 drivers/gpu/drm/drm_crtc.c    | 35 +++++++++++++++++++++++++++++++++++
 include/uapi/drm/drm_fourcc.h | 14 ++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 3007b44..2ac0d7c 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -3245,6 +3245,14 @@ static int format_check(const struct drm_mode_fb_cmd2 *r)
 	case DRM_FORMAT_YVU422:
 	case DRM_FORMAT_YUV444:
 	case DRM_FORMAT_YVU444:
+	case DRM_FORMAT_XRGB8888_A8:
+	case DRM_FORMAT_XBGR8888_A8:
+	case DRM_FORMAT_RGBX8888_A8:
+	case DRM_FORMAT_BGRX8888_A8:
+	case DRM_FORMAT_RGB888_A8:
+	case DRM_FORMAT_BGR888_A8:
+	case DRM_FORMAT_RGB565_A8:
+	case DRM_FORMAT_BGR565_A8:
 		return 0;
 	default:
 		DRM_DEBUG_KMS("invalid pixel format %s\n",
@@ -5198,11 +5206,15 @@ void drm_fb_get_bpp_depth(uint32_t format, unsigned int *depth,
 		break;
 	case DRM_FORMAT_RGB565:
 	case DRM_FORMAT_BGR565:
+	case DRM_FORMAT_RGB565_A8:
+	case DRM_FORMAT_BGR565_A8:
 		*depth = 16;
 		*bpp = 16;
 		break;
 	case DRM_FORMAT_RGB888:
 	case DRM_FORMAT_BGR888:
+	case DRM_FORMAT_RGB888_A8:
+	case DRM_FORMAT_BGR888_A8:
 		*depth = 24;
 		*bpp = 24;
 		break;
@@ -5210,6 +5222,10 @@ void drm_fb_get_bpp_depth(uint32_t format, unsigned int *depth,
 	case DRM_FORMAT_XBGR8888:
 	case DRM_FORMAT_RGBX8888:
 	case DRM_FORMAT_BGRX8888:
+	case DRM_FORMAT_XRGB8888_A8:
+	case DRM_FORMAT_XBGR8888_A8:
+	case DRM_FORMAT_RGBX8888_A8:
+	case DRM_FORMAT_BGRX8888_A8:
 		*depth = 24;
 		*bpp = 32;
 		break;
@@ -5268,6 +5284,14 @@ int drm_format_num_planes(uint32_t format)
 	case DRM_FORMAT_NV61:
 	case DRM_FORMAT_NV24:
 	case DRM_FORMAT_NV42:
+	case DRM_FORMAT_RGB565_A8:
+	case DRM_FORMAT_BGR565_A8:
+	case DRM_FORMAT_RGB888_A8:
+	case DRM_FORMAT_BGR888_A8:
+	case DRM_FORMAT_XRGB8888_A8:
+	case DRM_FORMAT_XBGR8888_A8:
+	case DRM_FORMAT_RGBX8888_A8:
+	case DRM_FORMAT_BGRX8888_A8:
 		return 2;
 	default:
 		return 1;
@@ -5315,6 +5339,17 @@ int drm_format_plane_cpp(uint32_t format, int plane)
 	case DRM_FORMAT_YUV444:
 	case DRM_FORMAT_YVU444:
 		return 1;
+	case DRM_FORMAT_RGB565_A8:
+	case DRM_FORMAT_BGR565_A8:
+		return plane ? 1 : 2;
+	case DRM_FORMAT_RGB888_A8:
+	case DRM_FORMAT_BGR888_A8:
+		return plane ? 1 : 3;
+	case DRM_FORMAT_XRGB8888_A8:
+	case DRM_FORMAT_XBGR8888_A8:
+	case DRM_FORMAT_RGBX8888_A8:
+	case DRM_FORMAT_BGRX8888_A8:
+		return plane ? 1 : 4;
 	default:
 		drm_fb_get_bpp_depth(format, &depth, &bpp);
 		return bpp >> 3;
diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
index 0773582..48d6ec8 100644
--- a/include/uapi/drm/drm_fourcc.h
+++ b/include/uapi/drm/drm_fourcc.h
@@ -96,6 +96,20 @@
 #define DRM_FORMAT_AYUV		fourcc_code('A', 'Y', 'U', 'V') /* [31:0] A:Y:Cb:Cr 8:8:8:8 little endian */
 
 /*
+ * 2 plane RGB + A
+ * index 0 = RGB plane
+ * index 1 = A plane
+ */
+#define DRM_FORMAT_XRGB8888_A8	fourcc_code('X', 'R', 'A', '8')
+#define DRM_FORMAT_XBGR8888_A8	fourcc_code('X', 'B', 'A', '8')
+#define DRM_FORMAT_RGBX8888_A8	fourcc_code('R', 'X', 'A', '8')
+#define DRM_FORMAT_BGRX8888_A8	fourcc_code('B', 'X', 'A', '8')
+#define DRM_FORMAT_RGB888_A8	fourcc_code('R', '8', 'A', '8')
+#define DRM_FORMAT_BGR888_A8	fourcc_code('B', '8', 'A', '8')
+#define DRM_FORMAT_RGB565_A8	fourcc_code('R', '5', 'A', '8')
+#define DRM_FORMAT_BGR565_A8	fourcc_code('B', '5', 'A', '8')
+
+/*
  * 2 plane YCbCr
  * index 0 = Y plane, [7:0] Y
  * index 1 = Cr:Cb plane, [15:0] Cr:Cb little endian
-- 
2.1.4