Based on kernel version 3.0.4. Page generated on 2011-10-03 22:07 EST.
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 <title>Return Value</title> 67 68 <para><function>ioctl()</function> returns <returnvalue>0</returnvalue> on 69 success. On failure, <returnvalue>-1</returnvalue> is returned, and the 70 <varname>errno</varname> variable is set appropriately. Generic error codes 71 are listed below, and request-specific error codes are listed in the 72 individual requests descriptions.</para> 73 <para>When an ioctl that takes an output or read/write parameter fails, 74 the parameter remains unmodified.</para> 75 76 <variablelist> 77 <varlistentry> 78 <term><errorcode>EBADF</errorcode></term> 79 <listitem> 80 <para><parameter>fd</parameter> is not a valid open file descriptor. 81 </para> 82 </listitem> 83 </varlistentry> 84 <varlistentry> 85 <term><errorcode>EFAULT</errorcode></term> 86 <listitem> 87 <para><parameter>argp</parameter> references an inaccessible memory 88 area.</para> 89 </listitem> 90 </varlistentry> 91 <varlistentry> 92 <term><errorcode>EINVAL</errorcode></term> 93 <listitem> 94 <para>The <parameter>request</parameter> or the data pointed to by 95 <parameter>argp</parameter> is not valid. This is a very common error 96 code, see the individual ioctl requests listed in 97 <xref linkend="media-user-func" /> for actual causes.</para> 98 </listitem> 99 </varlistentry> 100 <varlistentry> 101 <term><errorcode>ENOMEM</errorcode></term> 102 <listitem> 103 <para>Insufficient kernel memory was available to complete the 104 request.</para> 105 </listitem> 106 </varlistentry> 107 <varlistentry> 108 <term><errorcode>ENOTTY</errorcode></term> 109 <listitem> 110 <para><parameter>fd</parameter> is not associated with a character 111 special device.</para> 112 </listitem> 113 </varlistentry> 114 </variablelist> 115 </refsect1> 116 </refentry>
