[media] V4L: add Y12I, Y8I and Z16 pixel format documentation

Add documentation for 3 formats, used by RealSense cameras like R200.
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Documentation/DocBook/media/v4l/pixfmt-y12i.xml

+<refentry id="V4L2-PIX-FMT-Y12I">
+  <refmeta>
+    <refentrytitle>V4L2_PIX_FMT_Y12I ('Y12I')</refentrytitle>
+    &manvol;
+  </refmeta>
+  <refnamediv>
+    <refname><constant>V4L2_PIX_FMT_Y12I</constant></refname>
+    <refpurpose>Interleaved grey-scale image, e.g. from a stereo-pair</refpurpose>
+  </refnamediv>
+  <refsect1>
+    <title>Description</title>
+
+    <para>This is a grey-scale image with a depth of 12 bits per pixel, but with
+pixels from 2 sources interleaved and bit-packed. Each pixel is stored in a
+24-bit word in the little-endian order. On a little-endian machine these pixels
+can be deinterlaced using</para>
+
+<para>
+<programlisting>
+__u8 *buf;
+left0 = 0xfff &amp; *(__u16 *)buf;
+right0 = *(__u16 *)(buf + 1) >> 4;
+</programlisting>
+</para>
+
+    <example>
+      <title><constant>V4L2_PIX_FMT_Y12I</constant> 2 pixel data stream taking 3 bytes</title>
+
+      <formalpara>
+	<title>Bit-packed representation</title>
+	<para>pixels cross the byte boundary and have a ratio of 3 bytes for each
+          interleaved pixel.
+	  <informaltable frame="all">
+	    <tgroup cols="3" align="center">
+	      <colspec align="left" colwidth="2*" />
+	      <tbody valign="top">
+		<row>
+		  <entry>Y'<subscript>0left[7:0]</subscript></entry>
+		  <entry>Y'<subscript>0right[3:0]</subscript>Y'<subscript>0left[11:8]</subscript></entry>
+		  <entry>Y'<subscript>0right[11:4]</subscript></entry>
+		</row>
+	      </tbody>
+	    </tgroup>
+	  </informaltable>
+	</para>
+      </formalpara>
+    </example>
+  </refsect1>
+</refentry>

Documentation/DocBook/media/v4l/pixfmt-y8i.xml

+<refentry id="V4L2-PIX-FMT-Y8I">
+  <refmeta>
+    <refentrytitle>V4L2_PIX_FMT_Y8I ('Y8I ')</refentrytitle>
+    &manvol;
+  </refmeta>
+  <refnamediv>
+    <refname><constant>V4L2_PIX_FMT_Y8I</constant></refname>
+    <refpurpose>Interleaved grey-scale image, e.g. from a stereo-pair</refpurpose>
+  </refnamediv>
+  <refsect1>
+    <title>Description</title>
+
+    <para>This is a grey-scale image with a depth of 8 bits per pixel, but with
+pixels from 2 sources interleaved. Each pixel is stored in a 16-bit word. E.g.
+the R200 RealSense camera stores pixel from the left sensor in lower and from
+the right sensor in the higher 8 bits.</para>
+
+    <example>
+      <title><constant>V4L2_PIX_FMT_Y8I</constant> 4 &times; 4
+pixel image</title>
+
+      <formalpara>
+	<title>Byte Order.</title>
+	<para>Each cell is one byte.
+	  <informaltable frame="none">
+	    <tgroup cols="9" align="center">
+	      <colspec align="left" colwidth="2*" />
+	      <tbody valign="top">
+		<row>
+		  <entry>start&nbsp;+&nbsp;0:</entry>
+		  <entry>Y'<subscript>00left</subscript></entry>
+		  <entry>Y'<subscript>00right</subscript></entry>
+		  <entry>Y'<subscript>01left</subscript></entry>
+		  <entry>Y'<subscript>01right</subscript></entry>
+		  <entry>Y'<subscript>02left</subscript></entry>
+		  <entry>Y'<subscript>02right</subscript></entry>
+		  <entry>Y'<subscript>03left</subscript></entry>
+		  <entry>Y'<subscript>03right</subscript></entry>
+		</row>
+		<row>
+		  <entry>start&nbsp;+&nbsp;8:</entry>
+		  <entry>Y'<subscript>10left</subscript></entry>
+		  <entry>Y'<subscript>10right</subscript></entry>
+		  <entry>Y'<subscript>11left</subscript></entry>
+		  <entry>Y'<subscript>11right</subscript></entry>
+		  <entry>Y'<subscript>12left</subscript></entry>
+		  <entry>Y'<subscript>12right</subscript></entry>
+		  <entry>Y'<subscript>13left</subscript></entry>
+		  <entry>Y'<subscript>13right</subscript></entry>
+		</row>
+		<row>
+		  <entry>start&nbsp;+&nbsp;16:</entry>
+		  <entry>Y'<subscript>20left</subscript></entry>
+		  <entry>Y'<subscript>20right</subscript></entry>
+		  <entry>Y'<subscript>21left</subscript></entry>
+		  <entry>Y'<subscript>21right</subscript></entry>
+		  <entry>Y'<subscript>22left</subscript></entry>
+		  <entry>Y'<subscript>22right</subscript></entry>
+		  <entry>Y'<subscript>23left</subscript></entry>
+		  <entry>Y'<subscript>23right</subscript></entry>
+		</row>
+		<row>
+		  <entry>start&nbsp;+&nbsp;24:</entry>
+		  <entry>Y'<subscript>30left</subscript></entry>
+		  <entry>Y'<subscript>30right</subscript></entry>
+		  <entry>Y'<subscript>31left</subscript></entry>
+		  <entry>Y'<subscript>31right</subscript></entry>
+		  <entry>Y'<subscript>32left</subscript></entry>
+		  <entry>Y'<subscript>32right</subscript></entry>
+		  <entry>Y'<subscript>33left</subscript></entry>
+		  <entry>Y'<subscript>33right</subscript></entry>
+		</row>
+	      </tbody>
+	    </tgroup>
+	  </informaltable>
+	</para>
+      </formalpara>
+    </example>
+  </refsect1>
+</refentry>

Documentation/DocBook/media/v4l/pixfmt-z16.xml

+<refentry id="V4L2-PIX-FMT-Z16">
+  <refmeta>
+    <refentrytitle>V4L2_PIX_FMT_Z16 ('Z16 ')</refentrytitle>
+    &manvol;
+  </refmeta>
+  <refnamediv>
+    <refname><constant>V4L2_PIX_FMT_Z16</constant></refname>
+    <refpurpose>Interleaved grey-scale image, e.g. from a stereo-pair</refpurpose>
+  </refnamediv>
+  <refsect1>
+    <title>Description</title>
+
+    <para>This is a 16-bit format, representing depth data. Each pixel is a
+distance to the respective point in the image coordinates. Distance unit can
+vary and has to be negotiated with the device separately. Each pixel is stored
+in a 16-bit word in the little endian byte order.
+</para>
+
+    <example>
+      <title><constant>V4L2_PIX_FMT_Z16</constant> 4 &times; 4
+pixel image</title>
+
+      <formalpara>
+	<title>Byte Order.</title>
+	<para>Each cell is one byte.
+	  <informaltable frame="none">
+	    <tgroup cols="9" align="center">
+	      <colspec align="left" colwidth="2*" />
+	      <tbody valign="top">
+		<row>
+		  <entry>start&nbsp;+&nbsp;0:</entry>
+		  <entry>Z<subscript>00low</subscript></entry>
+		  <entry>Z<subscript>00high</subscript></entry>
+		  <entry>Z<subscript>01low</subscript></entry>
+		  <entry>Z<subscript>01high</subscript></entry>
+		  <entry>Z<subscript>02low</subscript></entry>
+		  <entry>Z<subscript>02high</subscript></entry>
+		  <entry>Z<subscript>03low</subscript></entry>
+		  <entry>Z<subscript>03high</subscript></entry>
+		</row>
+		<row>
+		  <entry>start&nbsp;+&nbsp;8:</entry>
+		  <entry>Z<subscript>10low</subscript></entry>
+		  <entry>Z<subscript>10high</subscript></entry>
+		  <entry>Z<subscript>11low</subscript></entry>
+		  <entry>Z<subscript>11high</subscript></entry>
+		  <entry>Z<subscript>12low</subscript></entry>
+		  <entry>Z<subscript>12high</subscript></entry>
+		  <entry>Z<subscript>13low</subscript></entry>
+		  <entry>Z<subscript>13high</subscript></entry>
+		</row>
+		<row>
+		  <entry>start&nbsp;+&nbsp;16:</entry>
+		  <entry>Z<subscript>20low</subscript></entry>
+		  <entry>Z<subscript>20high</subscript></entry>
+		  <entry>Z<subscript>21low</subscript></entry>
+		  <entry>Z<subscript>21high</subscript></entry>
+		  <entry>Z<subscript>22low</subscript></entry>
+		  <entry>Z<subscript>22high</subscript></entry>
+		  <entry>Z<subscript>23low</subscript></entry>
+		  <entry>Z<subscript>23high</subscript></entry>
+		</row>
+		<row>
+		  <entry>start&nbsp;+&nbsp;24:</entry>
+		  <entry>Z<subscript>30low</subscript></entry>
+		  <entry>Z<subscript>30high</subscript></entry>
+		  <entry>Z<subscript>31low</subscript></entry>
+		  <entry>Z<subscript>31high</subscript></entry>
+		  <entry>Z<subscript>32low</subscript></entry>
+		  <entry>Z<subscript>32high</subscript></entry>
+		  <entry>Z<subscript>33low</subscript></entry>
+		  <entry>Z<subscript>33high</subscript></entry>
+		</row>
+	      </tbody>
+	    </tgroup>
+	  </informaltable>
+	</para>
+      </formalpara>
+    </example>
+  </refsect1>
+</refentry>

Documentation/DocBook/media/v4l/pixfmt.xml

@@ -1620,6 +1620,8 @@ information.</para>
     &sub-y10b;
     &sub-y16;
     &sub-y16-be;
+    &sub-y8i;
+    &sub-y12i;
     &sub-uv8;
     &sub-yuyv;
     &sub-uyvy;
@@ -1642,6 +1644,14 @@ information.</para>
     &sub-m420;
   </section>
 
+  <section id="depth-formats">
+    <title>Depth Formats</title>
+    <para>Depth data provides distance to points, mapped onto the image plane
+    </para>
+
+    &sub-z16;
+  </section>
+
   <section>
     <title>Compressed Formats</title>