linux/Documentation/DocBook/media/v4l/func-munmap.xml
Sylwester Nawrocki c6401af669 [media] Remove unneeded comments from the media API DocBook files
This removes comment tags intended for emacs configuration from
67 files in the Media API DocBook. Such comments are not really
helpful and violate  the coding style rules.

Signed-off-by: Sylwester Nawrocki <snjw23@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-12-11 09:16:53 -02:00

77 lines
2.2 KiB
XML

<refentry id="func-munmap">
<refmeta>
<refentrytitle>V4L2 munmap()</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname>v4l2-munmap</refname>
<refpurpose>Unmap device memory</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>
#include &lt;unistd.h&gt;
#include &lt;sys/mman.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>munmap</function></funcdef>
<paramdef>void *<parameter>start</parameter></paramdef>
<paramdef>size_t <parameter>length</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>start</parameter></term>
<listitem>
<para>Address of the mapped buffer as returned by the
&func-mmap; function.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>length</parameter></term>
<listitem>
<para>Length of the mapped buffer. This must be the same
value as given to <function>mmap()</function> and returned by the
driver in the &v4l2-buffer; <structfield>length</structfield>
field for the single-planar API and in the &v4l2-plane;
<structfield>length</structfield> field for the multi-planar API.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>Unmaps a previously with the &func-mmap; function mapped
buffer and frees it, if possible. <!-- ? This function (not freeing)
has no impact on I/O in progress, specifically it does not imply
&VIDIOC-STREAMOFF; to terminate I/O. Unmapped buffers can still be
enqueued, dequeued or queried, they are just not accessible by the
application.--></para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success <function>munmap()</function> returns 0, on
failure -1 and the <varname>errno</varname> variable is set
appropriately:</para>
<variablelist>
<varlistentry>
<term><errorcode>EINVAL</errorcode></term>
<listitem>
<para>The <parameter>start</parameter> or
<parameter>length</parameter> is incorrect, or no buffers have been
mapped yet.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>