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- <refentry id="func-ioctl">
- <refmeta>
- <refentrytitle>V4L2 ioctl()</refentrytitle>
- &manvol;
- </refmeta>
- <refnamediv>
- <refname>v4l2-ioctl</refname>
- <refpurpose>Program a V4L2 device</refpurpose>
- </refnamediv>
- <refsynopsisdiv>
- <funcsynopsis>
- <funcsynopsisinfo>#include <sys/ioctl.h></funcsynopsisinfo>
- <funcprototype>
- <funcdef>int <function>ioctl</function></funcdef>
- <paramdef>int <parameter>fd</parameter></paramdef>
- <paramdef>int <parameter>request</parameter></paramdef>
- <paramdef>void *<parameter>argp</parameter></paramdef>
- </funcprototype>
- </funcsynopsis>
- </refsynopsisdiv>
- <refsect1>
- <title>Arguments</title>
- <variablelist>
- <varlistentry>
- <term><parameter>fd</parameter></term>
- <listitem>
- <para>&fd;</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><parameter>request</parameter></term>
- <listitem>
- <para>V4L2 ioctl request code as defined in the <filename>videodev2.h</filename> header file, for example
- VIDIOC_QUERYCAP.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><parameter>argp</parameter></term>
- <listitem>
- <para>Pointer to a function parameter, usually a structure.</para>
- </listitem>
- </varlistentry>
- </variablelist>
- </refsect1>
- <refsect1>
- <title>Description</title>
- <para>The <function>ioctl()</function> function is used to program
- V4L2 devices. The argument <parameter>fd</parameter> must be an open
- file descriptor. An ioctl <parameter>request</parameter> has encoded
- in it whether the argument is an input, output or read/write
- parameter, and the size of the argument <parameter>argp</parameter> in
- bytes. Macros and defines specifying V4L2 ioctl requests are located
- in the <filename>videodev2.h</filename> header file.
- Applications should use their own copy, not include the version in the
- kernel sources on the system they compile on. All V4L2 ioctl requests,
- their respective function and parameters are specified in <xref
- linkend="user-func" />.</para>
- </refsect1>
- <refsect1>
- &return-value;
- <para>When an ioctl that takes an output or read/write parameter fails,
- the parameter remains unmodified.</para>
- </refsect1>
- </refentry>
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