media: v4l2-ctrl: Add decoder conceal color control

Add decoder v4l2 control to set conceal color.
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst

@@ -674,6 +674,39 @@ enum v4l2_mpeg_video_frame_skip_mode -
     is currently displayed (decoded). This value is reset to 0 whenever
     the decoder is started.
 
+``V4L2_CID_MPEG_VIDEO_DEC_CONCEAL_COLOR (integer64)``
+    This control sets the conceal color in YUV color space. It describes
+    the client preference of the error conceal color in case of an error
+    where the reference frame is missing. The decoder should fill the
+    reference buffer with the preferred color and use it for future
+    decoding. The control is using 16 bits per channel.
+    Applicable to decoders.
+
+.. flat-table::
+    :header-rows:  0
+    :stub-columns: 0
+
+    * -
+      - 8bit  format
+      - 10bit format
+      - 12bit format
+    * - Y luminance
+      - Bit 0:7
+      - Bit 0:9
+      - Bit 0:11
+    * - Cb chrominance
+      - Bit 16:23
+      - Bit 16:25
+      - Bit 16:27
+    * - Cr chrominance
+      - Bit 32:39
+      - Bit 32:41
+      - Bit 32:43
+    * - Must be zero
+      - Bit 48:63
+      - Bit 48:63
+      - Bit 48:63
+
 ``V4L2_CID_MPEG_VIDEO_DECODER_SLICE_INTERFACE (boolean)``
     If enabled the decoder expects to receive a single slice per buffer,
     otherwise the decoder expects a single frame in per buffer.

drivers/media/v4l2-core/v4l2-ctrls.c

@@ -955,6 +955,7 @@ const char *v4l2_ctrl_get_name(u32 id)
 	case V4L2_CID_MPEG_VIDEO_VBV_SIZE:			return "VBV Buffer Size";
 	case V4L2_CID_MPEG_VIDEO_DEC_PTS:			return "Video Decoder PTS";
 	case V4L2_CID_MPEG_VIDEO_DEC_FRAME:			return "Video Decoder Frame Count";
+	case V4L2_CID_MPEG_VIDEO_DEC_CONCEAL_COLOR:		return "Video Decoder Conceal Color";
 	case V4L2_CID_MPEG_VIDEO_VBV_DELAY:			return "Initial Delay for VBV Control";
 	case V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE:		return "Horizontal MV Search Range";
 	case V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE:		return "Vertical MV Search Range";
@@ -1458,6 +1459,14 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
 		*max = 0x7fffffffffffffffLL;
 		*step = 1;
 		break;
+	case V4L2_CID_MPEG_VIDEO_DEC_CONCEAL_COLOR:
+		*type = V4L2_CTRL_TYPE_INTEGER64;
+		*min = 0;
+		/* default for 8 bit black, luma is 16, chroma is 128 */
+		*def = 0x8000800010LL;
+		*max = 0xffffffffffffLL;
+		*step = 1;
+		break;
 	case V4L2_CID_PIXEL_RATE:
 		*type = V4L2_CTRL_TYPE_INTEGER64;
 		*flags |= V4L2_CTRL_FLAG_READ_ONLY;

include/uapi/linux/v4l2-controls.h

@@ -432,6 +432,7 @@ enum v4l2_mpeg_video_multi_slice_mode {
 #define V4L2_CID_MPEG_VIDEO_LTR_COUNT			(V4L2_CID_CODEC_BASE+232)
 #define V4L2_CID_MPEG_VIDEO_FRAME_LTR_INDEX		(V4L2_CID_CODEC_BASE+233)
 #define V4L2_CID_MPEG_VIDEO_USE_LTR_FRAMES		(V4L2_CID_CODEC_BASE+234)
+#define V4L2_CID_MPEG_VIDEO_DEC_CONCEAL_COLOR		(V4L2_CID_CODEC_BASE+235)
 
 /* CIDs for the MPEG-2 Part 2 (H.262) codec */
 #define V4L2_CID_MPEG_VIDEO_MPEG2_LEVEL			(V4L2_CID_CODEC_BASE+270)