1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>V4L2 munmap()</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="LINUX MEDIA INFRASTRUCTURE API"><link rel="up" href="user-func.html" title="Appendix&#160;A.&#160;Function Reference"><link rel="prev" href="func-mmap.html" title="V4L2 mmap()"><link rel="next" href="func-open.html" title="V4L2 open()"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">V4L2 munmap()</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="func-mmap.html">Prev</a>&#160;</td><th width="60%" align="center">Appendix&#160;A.&#160;Function Reference</th><td width="20%" align="right">&#160;<a accesskey="n" href="func-open.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="func-munmap"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>v4l2-munmap &#8212; Unmap device memory</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">
2#include &lt;unistd.h&gt;
3#include &lt;sys/mman.h&gt;</pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">munmap</b>(</code></td><td>void *<var class="pdparam">start</var>, </td></tr><tr><td>&#160;</td><td>size_t <var class="pdparam">length</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1117023524"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>start</code></em></span></dt><dd><p>Address of the mapped buffer as returned by the
4<a class="link" href="func-mmap.html" title="V4L2 mmap()"><code class="function">mmap()</code></a> function.</p></dd><dt><span class="term"><em class="parameter"><code>length</code></em></span></dt><dd><p>Length of the mapped buffer. This must be the same
5value as given to <code class="function">mmap()</code> and returned by the
6driver in the struct&#160;<a class="link" href="buffer.html#v4l2-buffer" title="Table&#160;3.1.&#160;struct v4l2_buffer">v4l2_buffer</a> <em class="structfield"><code>length</code></em>
7field for the single-planar API and in the struct&#160;<a class="link" href="buffer.html#v4l2-plane" title="Table&#160;3.2.&#160;struct v4l2_plane">v4l2_plane</a>
8<em class="structfield"><code>length</code></em> field for the multi-planar API.</p></dd></dl></div></div><div class="refsect1"><a name="idp1117028340"></a><h2>Description</h2><p>Unmaps a previously with the <a class="link" href="func-mmap.html" title="V4L2 mmap()"><code class="function">mmap()</code></a> function mapped
9buffer and frees it, if possible. </p></div><div class="refsect1"><a name="idp1117029572"></a><h2>Return Value</h2><p>On success <code class="function">munmap()</code> returns 0, on
10failure -1 and the <code class="varname">errno</code> variable is set
11appropriately:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="errorcode">EINVAL</span></span></dt><dd><p>The <em class="parameter"><code>start</code></em> or
12<em class="parameter"><code>length</code></em> is incorrect, or no buffers have been
13mapped yet.</p></dd></dl></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="func-mmap.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="user-func.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="func-open.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">V4L2 mmap()&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;V4L2 open()</td></tr></table></div></body></html>
14