File-copy from v4.4.100
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Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/Documentation/DocBook/media/v4l/pixfmt-yuv420.xml b/Documentation/DocBook/media/v4l/pixfmt-yuv420.xml
new file mode 100644
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+ <refentry>
+ <refmeta>
+ <refentrytitle>V4L2_PIX_FMT_YVU420 ('YV12'), V4L2_PIX_FMT_YUV420 ('YU12')</refentrytitle>
+ &manvol;
+ </refmeta>
+ <refnamediv>
+ <refname id="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></refname>
+ <refname id="V4L2-PIX-FMT-YUV420"><constant>V4L2_PIX_FMT_YUV420</constant></refname>
+ <refpurpose>Planar formats with ½ horizontal and
+vertical chroma resolution, also known as YUV 4:2:0</refpurpose>
+ </refnamediv>
+ <refsect1>
+ <title>Description</title>
+
+ <para>These are planar formats, as opposed to a packed format.
+The three components are separated into three sub- images or planes.
+The Y plane is first. The Y plane has one byte per pixel. For
+<constant>V4L2_PIX_FMT_YVU420</constant>, the Cr plane immediately
+follows the Y plane in memory. The Cr plane is half the width and half
+the height of the Y plane (and of the image). Each Cr belongs to four
+pixels, a two-by-two square of the image. For example,
+Cr<subscript>0</subscript> belongs to Y'<subscript>00</subscript>,
+Y'<subscript>01</subscript>, Y'<subscript>10</subscript>, and
+Y'<subscript>11</subscript>. Following the Cr plane is the Cb plane,
+just like the Cr plane. <constant>V4L2_PIX_FMT_YUV420</constant> is
+the same except the Cb plane comes first, then the Cr plane.</para>
+
+ <para>If the Y plane has pad bytes after each row, then the Cr
+and Cb planes have half as many pad bytes after their rows. In other
+words, two Cx rows (including padding) is exactly as long as one Y row
+(including padding).</para>
+
+ <example>
+ <title><constant>V4L2_PIX_FMT_YVU420</constant> 4 × 4
+pixel image</title>
+
+ <formalpara>
+ <title>Byte Order.</title>
+ <para>Each cell is one byte.
+ <informaltable frame="none">
+ <tgroup cols="5" align="center">
+ <colspec align="left" colwidth="2*" />
+ <tbody valign="top">
+ <row>
+ <entry>start + 0:</entry>
+ <entry>Y'<subscript>00</subscript></entry>
+ <entry>Y'<subscript>01</subscript></entry>
+ <entry>Y'<subscript>02</subscript></entry>
+ <entry>Y'<subscript>03</subscript></entry>
+ </row>
+ <row>
+ <entry>start + 4:</entry>
+ <entry>Y'<subscript>10</subscript></entry>
+ <entry>Y'<subscript>11</subscript></entry>
+ <entry>Y'<subscript>12</subscript></entry>
+ <entry>Y'<subscript>13</subscript></entry>
+ </row>
+ <row>
+ <entry>start + 8:</entry>
+ <entry>Y'<subscript>20</subscript></entry>
+ <entry>Y'<subscript>21</subscript></entry>
+ <entry>Y'<subscript>22</subscript></entry>
+ <entry>Y'<subscript>23</subscript></entry>
+ </row>
+ <row>
+ <entry>start + 12:</entry>
+ <entry>Y'<subscript>30</subscript></entry>
+ <entry>Y'<subscript>31</subscript></entry>
+ <entry>Y'<subscript>32</subscript></entry>
+ <entry>Y'<subscript>33</subscript></entry>
+ </row>
+ <row>
+ <entry>start + 16:</entry>
+ <entry>Cr<subscript>00</subscript></entry>
+ <entry>Cr<subscript>01</subscript></entry>
+ </row>
+ <row>
+ <entry>start + 18:</entry>
+ <entry>Cr<subscript>10</subscript></entry>
+ <entry>Cr<subscript>11</subscript></entry>
+ </row>
+ <row>
+ <entry>start + 20:</entry>
+ <entry>Cb<subscript>00</subscript></entry>
+ <entry>Cb<subscript>01</subscript></entry>
+ </row>
+ <row>
+ <entry>start + 22:</entry>
+ <entry>Cb<subscript>10</subscript></entry>
+ <entry>Cb<subscript>11</subscript></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </para>
+ </formalpara>
+
+ <formalpara>
+ <title>Color Sample Location.</title>
+ <para>
+ <informaltable frame="none">
+ <tgroup cols="7" align="center">
+ <tbody valign="top">
+ <row>
+ <entry></entry>
+ <entry>0</entry><entry></entry><entry>1</entry><entry></entry>
+ <entry>2</entry><entry></entry><entry>3</entry>
+ </row>
+ <row>
+ <entry>0</entry>
+ <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
+ <entry>Y</entry><entry></entry><entry>Y</entry>
+ </row>
+ <row>
+ <entry></entry>
+ <entry></entry><entry>C</entry><entry></entry><entry></entry>
+ <entry></entry><entry>C</entry><entry></entry>
+ </row>
+ <row>
+ <entry>1</entry>
+ <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
+ <entry>Y</entry><entry></entry><entry>Y</entry>
+ </row>
+ <row>
+ <entry></entry>
+ </row>
+ <row>
+ <entry>2</entry>
+ <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
+ <entry>Y</entry><entry></entry><entry>Y</entry>
+ </row>
+ <row>
+ <entry></entry>
+ <entry></entry><entry>C</entry><entry></entry><entry></entry>
+ <entry></entry><entry>C</entry><entry></entry>
+ </row>
+ <row>
+ <entry>3</entry>
+ <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
+ <entry>Y</entry><entry></entry><entry>Y</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </para>
+ </formalpara>
+ </example>
+ </refsect1>
+ </refentry>