aboutsummaryrefslogtreecommitdiff
path: root/Documentation/DocBook/media/v4l/func-munmap.xml
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/DocBook/media/v4l/func-munmap.xml')
-rw-r--r--Documentation/DocBook/media/v4l/func-munmap.xml84
1 files changed, 84 insertions, 0 deletions
diff --git a/Documentation/DocBook/media/v4l/func-munmap.xml b/Documentation/DocBook/media/v4l/func-munmap.xml
new file mode 100644
index 00000000000..e2c4190f9bb
--- /dev/null
+++ b/Documentation/DocBook/media/v4l/func-munmap.xml
@@ -0,0 +1,84 @@
+<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>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->