docs: uapi: media: Document Raspberry Pi NV12 column format

The Raspberry Pi HEVC decoder uses a tiled format based on
columns for 8 and 10 bit YUV images, so document them as
NV12MT_COL128 and NV12MT_10_COL128.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

Documentation/userspace-api/media/v4l/pixfmt-yuv-planar.rst

@@ -955,6 +955,48 @@ Data in the 12 high bits, zeros in the 4 low bits, arranged in little endian ord
       - Cb\ :sub:`11`
       - Cr\ :sub:`11`
 
+V4L2_PIX_FMT_NV12MT_COL128 and V4L2_PIX_FMT_NV12MT_10_COL128
+------------------------------------------------------------
+
+``V4L2_PIX_FMT_NV12MT_COL128`` is a tiled version of
+``V4L2_PIX_FMT_NV12M`` where the two planes are split into 128 byte wide columns
+of Y or interleaved CbCr.
+
+V4L2_PIX_FMT_NV12MT_10_COL128 expands that as a 10 bit format where 3 10 bit
+values are packed into a 32bit word. A 128 byte wide column therefore holds 96
+samples (either Y or interleaved CrCb). That effectively makes it 6 values in a
+64 bit word for the CbCr plane, as the values always go in pairs.
+
+Bit-packed representation.
+
+.. tabularcolumns:: |p{1.2cm}||p{1.2cm}||p{1.2cm}||p{1.2cm}|p{3.2cm}|p{3.2cm}|
+
+.. flat-table::
+    :header-rows:  0
+    :stub-columns: 0
+    :widths: 8 8 8 8
+
+    * - Y'\ :sub:`00[7:0]`
+      - Y'\ :sub:`01[5:0] (bits 7--2)` Y'\ :sub:`00[9:8]`\ (bits 1--0)
+      - Y'\ :sub:`02[3:0] (bits 7--4)` Y'\ :sub:`01[9:6]`\ (bits 3--0)
+      - unused (bits 7--6)` Y'\ :sub:`02[9:4]`\ (bits 5--0)
+
+.. tabularcolumns:: |p{1.2cm}||p{1.2cm}||p{1.2cm}||p{1.2cm}|p{3.2cm}|p{3.2cm}|
+
+.. flat-table::
+    :header-rows:  0
+    :stub-columns: 0
+    :widths: 12 12 12 12 12 12 12 12
+
+    * - Cb\ :sub:`00[7:0]`
+      - Cr\ :sub:`00[5:0]`\ (bits 7--2) Cb\ :sub:`00[9:8]`\ (bits 1--0)
+      - Cb\ :sub:`01[3:0]`\ (bits 7--4) Cr\ :sub:`00[9:6]`\ (bits 3--0)
+      - unused (bits 7--6) Cb\ :sub:`02[9:4]`\ (bits 5--0)
+      - Cr\ :sub:`01[7:0]`
+      - Cb\ :sub:`02[5:0]`\ (bits 7--2) Cr\ :sub:`01[9:8]`\ (bits 1--0)
+      - Cr\ :sub:`02[3:0]`\ (bits 7--4) Cb\ :sub:`02[9:6]`\ (bits 3--0)
+      - unused (bits 7--6) Cr\ :sub:`02[9:4]`\ (bits 5--0)
+
 
 Fully Planar YUV Formats
 ========================