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Diffstat (limited to 'Documentation/DocBook/media/v4l/func-munmap.xml')
| -rw-r--r-- | Documentation/DocBook/media/v4l/func-munmap.xml | 76 |
1 files changed, 76 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 000000000..860d49ca5 --- /dev/null +++ b/Documentation/DocBook/media/v4l/func-munmap.xml @@ -0,0 +1,76 @@ +<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 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> |