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Laurent Pinchart97548ed2009-12-09 08:40:03 -03001<refentry id="media-ioc-setup-link">
2 <refmeta>
3 <refentrytitle>ioctl MEDIA_IOC_SETUP_LINK</refentrytitle>
4 &manvol;
5 </refmeta>
6
7 <refnamediv>
8 <refname>MEDIA_IOC_SETUP_LINK</refname>
9 <refpurpose>Modify the properties of a link</refpurpose>
10 </refnamediv>
11
12 <refsynopsisdiv>
13 <funcsynopsis>
14 <funcprototype>
15 <funcdef>int <function>ioctl</function></funcdef>
16 <paramdef>int <parameter>fd</parameter></paramdef>
17 <paramdef>int <parameter>request</parameter></paramdef>
18 <paramdef>struct media_link_desc *<parameter>argp</parameter></paramdef>
19 </funcprototype>
20 </funcsynopsis>
21 </refsynopsisdiv>
22
23 <refsect1>
24 <title>Arguments</title>
25
26 <variablelist>
27 <varlistentry>
28 <term><parameter>fd</parameter></term>
29 <listitem>
30 <para>File descriptor returned by
31 <link linkend='media-func-open'><function>open()</function></link>.</para>
32 </listitem>
33 </varlistentry>
34 <varlistentry>
35 <term><parameter>request</parameter></term>
36 <listitem>
37 <para>MEDIA_IOC_ENUM_LINKS</para>
38 </listitem>
39 </varlistentry>
40 <varlistentry>
41 <term><parameter>argp</parameter></term>
42 <listitem>
43 <para></para>
44 </listitem>
45 </varlistentry>
46 </variablelist>
47 </refsect1>
48
49 <refsect1>
50 <title>Description</title>
51
52 <para>To change link properties applications fill a &media-link-desc; with
53 link identification information (source and sink pad) and the new requested
54 link flags. They then call the MEDIA_IOC_SETUP_LINK ioctl with a pointer to
55 that structure.</para>
56 <para>The only configurable property is the <constant>ENABLED</constant>
57 link flag to enable/disable a link. Links marked with the
58 <constant>IMMUTABLE</constant> link flag can not be enabled or disabled.
59 </para>
60 <para>Link configuration has no side effect on other links. If an enabled
61 link at the sink pad prevents the link from being enabled, the driver
62 returns with an &EBUSY;.</para>
63 <para>If the specified link can't be found the driver returns with an
64 &EINVAL;.</para>
65 </refsect1>
66
67 <refsect1>
68 &return-value;
69
70 <variablelist>
71 <varlistentry>
72 <term><errorcode>EBUSY</errorcode></term>
73 <listitem>
74 <para>The link properties can't be changed because the link is
75 currently busy. This can be caused, for instance, by an active media
76 stream (audio or video) on the link. The ioctl shouldn't be retried if
77 no other action is performed before to fix the problem.</para>
78 </listitem>
79 </varlistentry>
80 <varlistentry>
81 <term><errorcode>EINVAL</errorcode></term>
82 <listitem>
83 <para>The &media-link-desc; references a non-existing link, or the
84 link is immutable and an attempt to modify its configuration was made.
85 </para>
86 </listitem>
87 </varlistentry>
88 </variablelist>
89 </refsect1>
90</refentry>