media: Add BGR48_12 video format

BGR48_12 is a reversed RGB format with 12 bits per component like BGR24,
expanded to 16bits.
Data in the 12 high bits, zeros in the 4 low bits,
arranged in little endian order.
Signed-off-by: Ming Qian <ming.qian@nxp.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Documentation/userspace-api/media/v4l/pixfmt-rgb.rst

@@ -956,6 +956,39 @@ number of bits for each component.
 
     \endgroup
 
+12 Bits Per Component
+==============================
+
+These formats store an RGB triplet in six or eight bytes, with 12 bits per component.
+Expand the bits per component to 16 bits, data in the high bits, zeros in the low bits,
+arranged in little endian order.
+
+.. raw:: latex
+
+    \small
+
+.. flat-table:: RGB Formats With 12 Bits Per Component
+    :header-rows:  1
+
+    * - Identifier
+      - Code
+      - Byte 1-0
+      - Byte 3-2
+      - Byte 5-4
+      - Byte 7-6
+    * .. _V4L2-PIX-FMT-BGR48-12:
+
+      - ``V4L2_PIX_FMT_BGR48_12``
+      - 'B312'
+
+      - B\ :sub:`15-4`
+      - G\ :sub:`15-4`
+      - R\ :sub:`15-4`
+      -
+
+.. raw:: latex
+
+    \normalsize
 
 Deprecated RGB Formats
 ======================

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

@@ -252,6 +252,7 @@ const struct v4l2_format_info *v4l2_format_info(u32 format)
 		{ .format = V4L2_PIX_FMT_RGB565,  .pixel_enc = V4L2_PIXEL_ENC_RGB, .mem_planes = 1, .comp_planes = 1, .bpp = { 2, 0, 0, 0 }, .hdiv = 1, .vdiv = 1 },
 		{ .format = V4L2_PIX_FMT_RGB555,  .pixel_enc = V4L2_PIXEL_ENC_RGB, .mem_planes = 1, .comp_planes = 1, .bpp = { 2, 0, 0, 0 }, .hdiv = 1, .vdiv = 1 },
 		{ .format = V4L2_PIX_FMT_BGR666,  .pixel_enc = V4L2_PIXEL_ENC_RGB, .mem_planes = 1, .comp_planes = 1, .bpp = { 4, 0, 0, 0 }, .hdiv = 1, .vdiv = 1 },
+		{ .format = V4L2_PIX_FMT_BGR48_12, .pixel_enc = V4L2_PIXEL_ENC_RGB, .mem_planes = 1, .comp_planes = 1, .bpp = { 6, 0, 0, 0 }, .hdiv = 1, .vdiv = 1 },
 
 		/* YUV packed formats */
 		{ .format = V4L2_PIX_FMT_YUYV,    .pixel_enc = V4L2_PIXEL_ENC_YUV, .mem_planes = 1, .comp_planes = 1, .bpp = { 2, 0, 0, 0 }, .hdiv = 2, .vdiv = 1 },

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

@@ -1298,6 +1298,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
 	case V4L2_PIX_FMT_RGBX1010102:	descr = "32-bit RGBX 10-10-10-2"; break;
 	case V4L2_PIX_FMT_RGBA1010102:	descr = "32-bit RGBA 10-10-10-2"; break;
 	case V4L2_PIX_FMT_ARGB2101010:	descr = "32-bit ARGB 2-10-10-10"; break;
+	case V4L2_PIX_FMT_BGR48_12:	descr = "12-bit Depth BGR"; break;
 	case V4L2_PIX_FMT_GREY:		descr = "8-bit Greyscale"; break;
 	case V4L2_PIX_FMT_Y4:		descr = "4-bit Greyscale"; break;
 	case V4L2_PIX_FMT_Y6:		descr = "6-bit Greyscale"; break;

include/uapi/linux/videodev2.h

@@ -580,6 +580,9 @@ struct v4l2_pix_format {
 #define V4L2_PIX_FMT_RGBA1010102 v4l2_fourcc('R', 'A', '3', '0') /* 32  RGBA-10-10-10-2 */
 #define V4L2_PIX_FMT_ARGB2101010 v4l2_fourcc('A', 'R', '3', '0') /* 32  ARGB-2-10-10-10 */
 
+/* RGB formats (6 or 8 bytes per pixel) */
+#define V4L2_PIX_FMT_BGR48_12    v4l2_fourcc('B', '3', '1', '2') /* 48  BGR 12-bit per component */
+
 /* Grey formats */
 #define V4L2_PIX_FMT_GREY    v4l2_fourcc('G', 'R', 'E', 'Y') /*  8  Greyscale     */
 #define V4L2_PIX_FMT_Y4      v4l2_fourcc('Y', '0', '4', ' ') /*  4  Greyscale     */