aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/DocBook/v4l/media-func-ioctl.xml
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/DocBook/v4l/media-func-ioctl.xml')
-rw-r--r--Documentation/DocBook/v4l/media-func-ioctl.xml116
1 files changed, 116 insertions, 0 deletions
diff --git a/Documentation/DocBook/v4l/media-func-ioctl.xml b/Documentation/DocBook/v4l/media-func-ioctl.xml
new file mode 100644
index 00000000..bda8604d
--- /dev/null
+++ b/Documentation/DocBook/v4l/media-func-ioctl.xml
@@ -0,0 +1,116 @@
+<refentry id="media-func-ioctl">
+ <refmeta>
+ <refentrytitle>media ioctl()</refentrytitle>
+ &manvol;
+ </refmeta>
+
+ <refnamediv>
+ <refname>media-ioctl</refname>
+ <refpurpose>Control a media device</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include &lt;sys/ioctl.h&gt;</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>Media ioctl request code as defined in the media.h header file,
+ for example MEDIA_IOC_SETUP_LINK.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>argp</parameter></term>
+ <listitem>
+ <para>Pointer to a request-specific structure.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Description</title>
+ <para>The <function>ioctl()</function> function manipulates media device
+ parameters. The argument <parameter>fd</parameter> must be an open file
+ descriptor.</para>
+ <para>The ioctl <parameter>request</parameter> code specifies the media
+ function to be called. It 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.</para>
+ <para>Macros and structures definitions specifying media ioctl requests and
+ their parameters are located in the media.h header file. All media ioctl
+ requests, their respective function and parameters are specified in
+ <xref linkend="media-user-func" />.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Return Value</title>
+
+ <para><function>ioctl()</function> returns <returnvalue>0</returnvalue> on
+ success. On failure, <returnvalue>-1</returnvalue> is returned, and the
+ <varname>errno</varname> variable is set appropriately. Generic error codes
+ are listed below, and request-specific error codes are listed in the
+ individual requests descriptions.</para>
+ <para>When an ioctl that takes an output or read/write parameter fails,
+ the parameter remains unmodified.</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><errorcode>EBADF</errorcode></term>
+ <listitem>
+ <para><parameter>fd</parameter> is not a valid open file descriptor.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>EFAULT</errorcode></term>
+ <listitem>
+ <para><parameter>argp</parameter> references an inaccessible memory
+ area.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>EINVAL</errorcode></term>
+ <listitem>
+ <para>The <parameter>request</parameter> or the data pointed to by
+ <parameter>argp</parameter> is not valid. This is a very common error
+ code, see the individual ioctl requests listed in
+ <xref linkend="media-user-func" /> for actual causes.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>ENOMEM</errorcode></term>
+ <listitem>
+ <para>Insufficient kernel memory was available to complete the
+ request.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>ENOTTY</errorcode></term>
+ <listitem>
+ <para><parameter>fd</parameter> is not associated with a character
+ special device.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>