84 lines
2.2 KiB
XML
84 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 <unistd.h>
|
|
#include <sys/mman.h></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.</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>
|
|
|
|
<!--
|
|
Local Variables:
|
|
mode: sgml
|
|
sgml-parent-document: "v4l2.sgml"
|
|
indent-tabs-mode: nil
|
|
End:
|
|
-->
|