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+<refentry id="media-ioc-enum-links">
+  <refmeta>
+    <refentrytitle>ioctl MEDIA_IOC_ENUM_LINKS</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>MEDIA_IOC_ENUM_LINKS</refname>
+    <refpurpose>Enumerate all pads and links for a given entity</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcprototype>
+	<funcdef>int <function>ioctl</function></funcdef>
+	<paramdef>int <parameter>fd</parameter></paramdef>
+	<paramdef>int <parameter>request</parameter></paramdef>
+	<paramdef>struct media_links_enum *<parameter>argp</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>File descriptor returned by
+	  <link linkend='media-func-open'><function>open()</function></link>.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>request</parameter></term>
+	<listitem>
+	  <para>MEDIA_IOC_ENUM_LINKS</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para></para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>To enumerate pads and/or links for a given entity, applications set
+    the entity field of a &media-links-enum; structure and initialize the
+    &media-pad-desc; and &media-link-desc; structure arrays pointed by the
+    <structfield>pads</structfield> and <structfield>links</structfield> fields.
+    They then call the MEDIA_IOC_ENUM_LINKS ioctl with a pointer to this
+    structure.</para>
+    <para>If the <structfield>pads</structfield> field is not NULL, the driver
+    fills the <structfield>pads</structfield> array with information about the
+    entity's pads. The array must have enough room to store all the entity's
+    pads. The number of pads can be retrieved with the &MEDIA-IOC-ENUM-ENTITIES;
+    ioctl.</para>
+    <para>If the <structfield>links</structfield> field is not NULL, the driver
+    fills the <structfield>links</structfield> array with information about the
+    entity's outbound links. The array must have enough room to store all the
+    entity's outbound links. The number of outbound links can be retrieved with
+    the &MEDIA-IOC-ENUM-ENTITIES; ioctl.</para>
+    <para>Only forward links that originate at one of the entity's source pads
+    are returned during the enumeration process.</para>
+
+    <table pgwide="1" frame="none" id="media-links-enum">
+      <title>struct <structname>media_links_enum</structname></title>
+      <tgroup cols="3">
+        &cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>entity</structfield></entry>
+	    <entry>Entity id, set by the application.</entry>
+	  </row>
+	  <row>
+	    <entry>&media-pad-desc;</entry>
+	    <entry>*<structfield>pads</structfield></entry>
+	    <entry>Pointer to a pads array allocated by the application. Ignored
+	    if NULL.</entry>
+	  </row>
+	  <row>
+	    <entry>&media-link-desc;</entry>
+	    <entry>*<structfield>links</structfield></entry>
+	    <entry>Pointer to a links array allocated by the application. Ignored
+	    if NULL.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table pgwide="1" frame="none" id="media-pad-desc">
+      <title>struct <structname>media_pad_desc</structname></title>
+      <tgroup cols="3">
+        &cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>entity</structfield></entry>
+	    <entry>ID of the entity this pad belongs to.</entry>
+	  </row>
+	  <row>
+	    <entry>__u16</entry>
+	    <entry><structfield>index</structfield></entry>
+	    <entry>0-based pad index.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>flags</structfield></entry>
+	    <entry>Pad flags, see <xref linkend="media-pad-flag" /> for more details.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="media-pad-flag">
+      <title>Media pad flags</title>
+      <tgroup cols="2">
+        <colspec colname="c1"/>
+        <colspec colname="c2"/>
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>MEDIA_PAD_FL_SINK</constant></entry>
+	    <entry>Input pad, relative to the entity. Input pads sink data and
+	    are targets of links.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_PAD_FL_SOURCE</constant></entry>
+	    <entry>Output pad, relative to the entity. Output pads source data
+	    and are origins of links.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_PAD_FL_MUST_CONNECT</constant></entry>
+	    <entry>If this flag is set and the pad is linked to any other
+	    pad, then at least one of those links must be enabled for the
+	    entity to be able to stream. There could be temporary reasons
+	    (e.g. device configuration dependent) for the pad to need
+	    enabled links even when this flag isn't set; the absence of the
+	    flag doesn't imply there is none.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table pgwide="1" frame="none" id="media-link-desc">
+      <title>struct <structname>media_link_desc</structname></title>
+      <tgroup cols="3">
+        &cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>&media-pad-desc;</entry>
+	    <entry><structfield>source</structfield></entry>
+	    <entry>Pad at the origin of this link.</entry>
+	  </row>
+	  <row>
+	    <entry>&media-pad-desc;</entry>
+	    <entry><structfield>sink</structfield></entry>
+	    <entry>Pad at the target of this link.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>flags</structfield></entry>
+	    <entry>Link flags, see <xref linkend="media-link-flag" /> for more details.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="media-link-flag">
+      <title>Media link flags</title>
+      <tgroup cols="2">
+        <colspec colname="c1"/>
+        <colspec colname="c2"/>
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>MEDIA_LNK_FL_ENABLED</constant></entry>
+	    <entry>The link is enabled and can be used to transfer media data.
+	    When two or more links target a sink pad, only one of them can be
+	    enabled at a time.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_LNK_FL_IMMUTABLE</constant></entry>
+	    <entry>The link enabled state can't be modified at runtime. An
+	    immutable link is always enabled.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_LNK_FL_DYNAMIC</constant></entry>
+	    <entry>The link enabled state can be modified during streaming. This
+	    flag is set by drivers and is read-only for applications.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+    <para>One and only one of <constant>MEDIA_PAD_FL_SINK</constant> and
+    <constant>MEDIA_PAD_FL_SOURCE</constant> must be set for every pad.</para>
+  </refsect1>
+
+  <refsect1>
+    &return-value;
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>EINVAL</errorcode></term>
+	<listitem>
+	  <para>The &media-links-enum; <structfield>id</structfield> references
+	  a non-existing entity.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>