V4L/DVB (12761): DocBook: add media API specs

The V4L and DVB API's are there for a long time. however, up to now,
no efforts were done to merge them to kernel DocBook.

This patch adds the current versions of the specs as an unique compendium.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/DocBook/v4l/vidioc-g-output.xml

@@ -0,0 +1,100 @@
+<refentry id="vidioc-g-output">
+  <refmeta>
+    <refentrytitle>ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>VIDIOC_G_OUTPUT</refname>
+    <refname>VIDIOC_S_OUTPUT</refname>
+    <refpurpose>Query or select the current video output</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcprototype>
+	<funcdef>int <function>ioctl</function></funcdef>
+	<paramdef>int <parameter>fd</parameter></paramdef>
+	<paramdef>int <parameter>request</parameter></paramdef>
+	<paramdef>int *<parameter>argp</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>&fd;</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>request</parameter></term>
+	<listitem>
+	  <para>VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para></para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>To query the current video output applications call the
+<constant>VIDIOC_G_OUTPUT</constant> ioctl with a pointer to an integer
+where the driver stores the number of the output, as in the
+&v4l2-output; <structfield>index</structfield> field. This ioctl
+will fail only when there are no video outputs, returning the
+&EINVAL;.</para>
+
+    <para>To select a video output applications store the number of the
+desired output in an integer and call the
+<constant>VIDIOC_S_OUTPUT</constant> ioctl with a pointer to this integer.
+Side effects are possible. For example outputs may support different
+video standards, so the driver may implicitly switch the current
+standard. It is good practice to select an output before querying or
+negotiating any other parameters.</para>
+
+    <para>Information about video outputs is available using the
+&VIDIOC-ENUMOUTPUT; ioctl.</para>
+  </refsect1>
+
+  <refsect1>
+    &return-value;
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>EINVAL</errorcode></term>
+	<listitem>
+	  <para>The number of the video output is out of bounds, or
+there are no video outputs at all and this ioctl is not
+supported.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>EBUSY</errorcode></term>
+	<listitem>
+	  <para>I/O is in progress, the output cannot be
+switched.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->