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<refentry id="media-g-topology">
<refmeta>
<refentrytitle>ioctl MEDIA_IOC_G_TOPOLOGY</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname>MEDIA_IOC_G_TOPOLOGY</refname>
<refpurpose>Enumerate the graph topology and graph element properties</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_v2_topology *<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_G_TOPOLOGY</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>argp</parameter></term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>The typical usage of this ioctl is to call it twice.
On the first call, the structure defined at &media-v2-topology; should
be zeroed. At return, if no errors happen, this ioctl will return the
<constant>topology_version</constant> and the total number of entities,
interfaces, pads and links.</para>
<para>Before the second call, the userspace should allocate arrays to
store the graph elements that are desired, putting the pointers to them
at the ptr_entities, ptr_interfaces, ptr_links and/or ptr_pads, keeping
the other values untouched.</para>
<para>If the <constant>topology_version</constant> remains the same, the
ioctl should fill the desired arrays with the media graph elements.</para>
<table pgwide="1" frame="none" id="media-v2-topology">
<title>struct <structname>media_v2_topology</structname></title>
<tgroup cols="5">
<colspec colname="c1" />
<colspec colname="c2" />
<colspec colname="c3" />
<colspec colname="c4" />
<colspec colname="c5" />
<tbody valign="top">
<row>
<entry>__u64</entry>
<entry><structfield>topology_version</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Version of the media graph topology. When the graph is
created, this field starts with zero. Every time a graph
element is added or removed, this field is
incremented.</entry>
</row>
<row>
<entry>__u64</entry>
<entry><structfield>num_entities</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Number of entities in the graph</entry>
</row>
<row>
<entry>__u64</entry>
<entry><structfield>ptr_entities</structfield></entry>
<entry></entry>
<entry></entry>
<entry>A pointer to a memory area where the entities array
will be stored, converted to a 64-bits integer.
It can be zero. if zero, the ioctl won't store the
entities. It will just update
<constant>num_entities</constant></entry>
</row>
<row>
<entry>__u64</entry>
<entry><structfield>num_interfaces</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Number of interfaces in the graph</entry>
</row>
<row>
<entry>__u64</entry>
<entry><structfield>ptr_interfaces</structfield></entry>
<entry></entry>
<entry></entry>
<entry>A pointer to a memory area where the interfaces array
will be stored, converted to a 64-bits integer.
It can be zero. if zero, the ioctl won't store the
interfaces. It will just update
<constant>num_interfaces</constant></entry>
</row>
<row>
<entry>__u64</entry>
<entry><structfield>num_pads</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Total number of pads in the graph</entry>
</row>
<row>
<entry>__u64</entry>
<entry><structfield>ptr_pads</structfield></entry>
<entry></entry>
<entry></entry>
<entry>A pointer to a memory area where the pads array
will be stored, converted to a 64-bits integer.
It can be zero. if zero, the ioctl won't store the
pads. It will just update
<constant>num_pads</constant></entry>
</row>
<row>
<entry>__u64</entry>
<entry><structfield>num_links</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Total number of data and interface links in the graph</entry>
</row>
<row>
<entry>__u64</entry>
<entry><structfield>ptr_links</structfield></entry>
<entry></entry>
<entry></entry>
<entry>A pointer to a memory area where the links array
will be stored, converted to a 64-bits integer.
It can be zero. if zero, the ioctl won't store the
links. It will just update
<constant>num_links</constant></entry>
</row>
</tbody>
</tgroup>
</table>
<table pgwide="1" frame="none" id="media-v2-entity">
<title>struct <structname>media_v2_entity</structname></title>
<tgroup cols="5">
<colspec colname="c1" />
<colspec colname="c2" />
<colspec colname="c3" />
<colspec colname="c4" />
<colspec colname="c5" />
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>id</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Unique ID for the entity.</entry>
</row>
<row>
<entry>char</entry>
<entry><structfield>name</structfield>[64]</entry>
<entry></entry>
<entry></entry>
<entry>Entity name as an UTF-8 NULL-terminated string.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>function</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Entity main function, see <xref linkend="media-entity-type" /> for details.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>reserved</structfield>[12]</entry>
<entry>Reserved for future extensions. Drivers and applications must
set this array to zero.</entry>
</row>
</tbody>
</tgroup>
</table>
<table pgwide="1" frame="none" id="media-v2-interface">
<title>struct <structname>media_v2_interface</structname></title>
<tgroup cols="5">
<colspec colname="c1" />
<colspec colname="c2" />
<colspec colname="c3" />
<colspec colname="c4" />
<colspec colname="c5" />
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>id</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Unique ID for the interface.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>intf_type</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Interface type, see <xref linkend="media-intf-type" /> for details.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>flags</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Interface flags. Currently unused.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>reserved</structfield>[9]</entry>
<entry></entry>
<entry></entry>
<entry>Reserved for future extensions. Drivers and applications must
set this array to zero.</entry>
</row>
<row>
<entry>struct media_v2_intf_devnode</entry>
<entry><structfield>devnode</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Used only for device node interfaces. See <xref linkend="media-v2-intf-devnode" /> for details..</entry>
</row>
</tbody>
</tgroup>
</table>
<table pgwide="1" frame="none" id="media-v2-intf-devnode">
<title>struct <structname>media_v2_interface</structname></title>
<tgroup cols="5">
<colspec colname="c1" />
<colspec colname="c2" />
<colspec colname="c3" />
<colspec colname="c4" />
<colspec colname="c5" />
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>major</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Device node major number.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>minor</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Device node minor number.</entry>
</row>
</tbody>
</tgroup>
</table>
<table pgwide="1" frame="none" id="media-v2-pad">
<title>struct <structname>media_v2_pad</structname></title>
<tgroup cols="5">
<colspec colname="c1" />
<colspec colname="c2" />
<colspec colname="c3" />
<colspec colname="c4" />
<colspec colname="c5" />
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>id</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Unique ID for the pad.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>entity_id</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Unique ID for the entity where this pad belongs.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>flags</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Pad flags, see <xref linkend="media-pad-flag" /> for more details.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>reserved</structfield>[9]</entry>
<entry></entry>
<entry></entry>
<entry>Reserved for future extensions. Drivers and applications must
set this array to zero.</entry>
</row>
</tbody>
</tgroup>
</table>
<table pgwide="1" frame="none" id="media-v2-link">
<title>struct <structname>media_v2_pad</structname></title>
<tgroup cols="5">
<colspec colname="c1" />
<colspec colname="c2" />
<colspec colname="c3" />
<colspec colname="c4" />
<colspec colname="c5" />
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>id</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Unique ID for the pad.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>source_id</structfield></entry>
<entry></entry>
<entry></entry>
<entry>
<para>On pad to pad links: unique ID for the source pad.</para>
<para>On interface to entity links: unique ID for the interface.</para>
</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>sink_id</structfield></entry>
<entry></entry>
<entry></entry>
<entry>
<para>On pad to pad links: unique ID for the sink pad.</para>
<para>On interface to entity links: unique ID for the entity.</para>
</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>flags</structfield></entry>
<entry></entry>
<entry></entry>
<entry>Link flags, see <xref linkend="media-link-flag" /> for more details.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>reserved</structfield>[5]</entry>
<entry></entry>
<entry></entry>
<entry>Reserved for future extensions. Drivers and applications must
set this array to zero.</entry>
</row>
</tbody>
</tgroup>
</table>
</refsect1>
<refsect1>
&return-value;
<variablelist>
<varlistentry>
<term><errorcode>ENOSPC</errorcode></term>
<listitem>
<para>This is returned when either one or more of the num_entities,
num_interfaces, num_links or num_pads are non-zero and are smaller
than the actual number of elements inside the graph. This may happen
if the <constant>topology_version</constant> changed when compared
to the last time this ioctl was called. Userspace should usually
free the area for the pointers, zero the struct elements and call
this ioctl again.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
|
