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Diffstat (limited to 'Documentation/DocBook/media/v4l/func-ioctl.xml')
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1 | <refentry id="func-ioctl"> | ||
2 | <refmeta> | ||
3 | <refentrytitle>V4L2 ioctl()</refentrytitle> | ||
4 | &manvol; | ||
5 | </refmeta> | ||
6 | |||
7 | <refnamediv> | ||
8 | <refname>v4l2-ioctl</refname> | ||
9 | <refpurpose>Program a V4L2 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>V4L2 ioctl request code as defined in the <filename>videodev2.h</filename> header file, for example | ||
38 | VIDIOC_QUERYCAP.</para> | ||
39 | </listitem> | ||
40 | </varlistentry> | ||
41 | <varlistentry> | ||
42 | <term><parameter>argp</parameter></term> | ||
43 | <listitem> | ||
44 | <para>Pointer to a function parameter, usually a structure.</para> | ||
45 | </listitem> | ||
46 | </varlistentry> | ||
47 | </variablelist> | ||
48 | </refsect1> | ||
49 | |||
50 | <refsect1> | ||
51 | <title>Description</title> | ||
52 | |||
53 | <para>The <function>ioctl()</function> function is used to program | ||
54 | V4L2 devices. The argument <parameter>fd</parameter> must be an open | ||
55 | file descriptor. An ioctl <parameter>request</parameter> has encoded | ||
56 | in it whether the argument is an input, output or read/write | ||
57 | parameter, and the size of the argument <parameter>argp</parameter> in | ||
58 | bytes. Macros and defines specifying V4L2 ioctl requests are located | ||
59 | in the <filename>videodev2.h</filename> header file. | ||
60 | Applications should use their own copy, not include the version in the | ||
61 | kernel sources on the system they compile on. All V4L2 ioctl requests, | ||
62 | their respective function and parameters are specified in <xref | ||
63 | linkend="user-func" />.</para> | ||
64 | </refsect1> | ||
65 | |||
66 | <refsect1> | ||
67 | &return-value; | ||
68 | <para>When an ioctl that takes an output or read/write parameter fails, | ||
69 | the parameter remains unmodified.</para> | ||
70 | </refsect1> | ||
71 | </refentry> | ||
72 | |||
73 | <!-- | ||
74 | Local Variables: | ||
75 | mode: sgml | ||
76 | sgml-parent-document: "v4l2.sgml" | ||
77 | indent-tabs-mode: nil | ||
78 | End: | ||
79 | --> | ||