Based on kernel version 4.7.2. Page generated on 2016-08-22 22:45 EST.
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>
