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Diffstat (limited to 'Documentation/DocBook/media/v4l/media-func-ioctl.xml')
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1 | <refentry id="media-func-ioctl"> | ||
2 | <refmeta> | ||
3 | <refentrytitle>media ioctl()</refentrytitle> | ||
4 | &manvol; | ||
5 | </refmeta> | ||
6 | |||
7 | <refnamediv> | ||
8 | <refname>media-ioctl</refname> | ||
9 | <refpurpose>Control a media device</refpurpose> | ||
10 | </refnamediv> | ||
11 | |||
12 | <refsynopsisdiv> | ||
13 | <funcsynopsis> | ||
14 | <funcsynopsisinfo>#include <sys/ioctl.h></funcsynopsisinfo> | ||
15 | <funcprototype> | ||
16 | <funcdef>int <function>ioctl</function></funcdef> | ||
17 | <paramdef>int <parameter>fd</parameter></paramdef> | ||
18 | <paramdef>int <parameter>request</parameter></paramdef> | ||
19 | <paramdef>void *<parameter>argp</parameter></paramdef> | ||
20 | </funcprototype> | ||
21 | </funcsynopsis> | ||
22 | </refsynopsisdiv> | ||
23 | |||
24 | <refsect1> | ||
25 | <title>Arguments</title> | ||
26 | |||
27 | <variablelist> | ||
28 | <varlistentry> | ||
29 | <term><parameter>fd</parameter></term> | ||
30 | <listitem> | ||
31 | <para>&fd;</para> | ||
32 | </listitem> | ||
33 | </varlistentry> | ||
34 | <varlistentry> | ||
35 | <term><parameter>request</parameter></term> | ||
36 | <listitem> | ||
37 | <para>Media ioctl request code as defined in the media.h header file, | ||
38 | for example MEDIA_IOC_SETUP_LINK.</para> | ||
39 | </listitem> | ||
40 | </varlistentry> | ||
41 | <varlistentry> | ||
42 | <term><parameter>argp</parameter></term> | ||
43 | <listitem> | ||
44 | <para>Pointer to a request-specific structure.</para> | ||
45 | </listitem> | ||
46 | </varlistentry> | ||
47 | </variablelist> | ||
48 | </refsect1> | ||
49 | |||
50 | <refsect1> | ||
51 | <title>Description</title> | ||
52 | <para>The <function>ioctl()</function> function manipulates media device | ||
53 | parameters. The argument <parameter>fd</parameter> must be an open file | ||
54 | descriptor.</para> | ||
55 | <para>The ioctl <parameter>request</parameter> code specifies the media | ||
56 | function to be called. It has encoded in it whether the argument is an | ||
57 | input, output or read/write parameter, and the size of the argument | ||
58 | <parameter>argp</parameter> in bytes.</para> | ||
59 | <para>Macros and structures definitions specifying media ioctl requests and | ||
60 | their parameters are located in the media.h header file. All media ioctl | ||
61 | requests, their respective function and parameters are specified in | ||
62 | <xref linkend="media-user-func" />.</para> | ||
63 | </refsect1> | ||
64 | |||
65 | <refsect1> | ||
66 | &return-value; | ||
67 | |||
68 | <para>Request-specific error codes are listed in the | ||
69 | individual requests descriptions.</para> | ||
70 | <para>When an ioctl that takes an output or read/write parameter fails, | ||
71 | the parameter remains unmodified.</para> | ||
72 | </refsect1> | ||
73 | </refentry> | ||