<?xml version="1.0" encoding="ANSI_X3.4-1968" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><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 V1.75.2" /><link rel="home" href="index.html" title="LINUX MEDIA INFRASTRUCTURE API" /><link rel="up" href="apa.html" title="Appendix A. Function Reference" /><link rel="prev" href="re62.html" title="V4L2 mmap()" /><link rel="next" href="re64.html" title="V4L2 open()" /></head><body><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="re62.html">Prev</a> </td><th width="60%" align="center">Appendix A. Function Reference</th><td width="20%" align="right"> <a accesskey="n" href="re64.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="V4L2 munmap()"><a id="func-munmap"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>v4l2-munmap — Unmap device memory</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo"> #include <unistd.h> #include <sys/mman.h></pre><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">munmap</b>(</code></td><td>void *<var class="pdparam">start</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">length</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id2740102"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>start</code></em></span></dt><dd><p>Address of the mapped buffer as returned by the <a class="link" href="re62.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 value as given to <code class="function">mmap()</code> and returned by the driver in the struct <a class="link" href="ch03s05.html#v4l2-buffer" title="Table 3.1. struct v4l2_buffer">v4l2_buffer</a> <em class="structfield"><code>length</code></em> field.</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id2740174"></a><h2>Description</h2><p>Unmaps a previously with the <a class="link" href="re62.html" title="V4L2 mmap()"><code class="function">mmap()</code></a> function mapped buffer and frees it, if possible. </p></div><div class="refsect1" title="Return Value"><a id="id2740194"></a><h2>Return Value</h2><p>On success <code class="function">munmap()</code> returns 0, on failure -1 and the <code class="varname">errno</code> variable is set appropriately:</p><div class="variablelist"><dl><dt><span class="term"><span class="errorcode">EINVAL</span></span></dt><dd><p>The <em class="parameter"><code>start</code></em> or <em class="parameter"><code>length</code></em> is incorrect, or no buffers have been mapped 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="re62.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="apa.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re64.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">V4L2 mmap() </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> V4L2 open()</td></tr></table></div></body></html>
