Documentation/userspace-api/media/v4l/func-munmap.rst

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.. document under the terms of the GNU Free Documentation License,
.. Version 1.1 or any later version published by the Free Software
.. Foundation, with no Invariant Sections, no Front-Cover Texts
.. and no Back-Cover Texts. A copy of the license is included at
.. Documentation/userspace-api/media/fdl-appendix.rst.
..
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections

.. _func-munmap:

*************
V4L2 munmap()
*************

Name
====

v4l2-munmap - Unmap device memory


Synopsis
========

.. code-block:: c

    #include <unistd.h>
    #include <sys/mman.h>


.. c:function:: int munmap( void *start, size_t length )
    :name: v4l2-munmap

Arguments
=========

``start``
    Address of the mapped buffer as returned by the
    :ref:`mmap() <func-mmap>` function.

``length``
    Length of the mapped buffer. This must be the same value as given to
    :ref:`mmap() <func-mmap>` and returned by the driver in the struct
    :c:type:`v4l2_buffer` ``length`` field for the
    single-planar API and in the struct
    :c:type:`v4l2_plane` ``length`` field for the
    multi-planar API.


Description
===========

Unmaps a previously with the :ref:`mmap() <func-mmap>` function mapped
buffer and frees it, if possible.


Return Value
============

On success :ref:`munmap() <func-munmap>` returns 0, on failure -1 and the
``errno`` variable is set appropriately:

EINVAL
    The ``start`` or ``length`` is incorrect, or no buffers have been
    mapped yet.