linux/Documentation/DocBook/media/v4l/func-munmap.xml
Mauro Carvalho Chehab 4266129964 [media] DocBook: Move all media docbook stuff into its own directory
This patch addresses several issues pointed by Randy Dunlap
<rdunlap@xenotime.net> at changeset ece722c:

- In the generated index.html file, "media" is listed first, but it
  should be listed in alphabetical order, not first.

- The generated files are (hidden) in .tmpmedia/

- The link from the top-level index.html file to "media" is to
  media/index.html, but the file is actually in .tmpmedia/media/index.html

- Please build docs with and without using "O=builddir" and test that.

- Would it be possible for media to have its own Makefile instead of
  merging into this one?

Due to the way cleandocs target works, I had to rename the media DocBook
to media_api, otherwise cleandocs would remove the /media directory.

Thanks-to: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:05 -03:00

85 lines
2.3 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>
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