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authorMauro Carvalho Chehab <mchehab+huawei@kernel.org>2020-09-24 14:04:26 +0200
committerMauro Carvalho Chehab <mchehab+huawei@kernel.org>2020-10-15 07:49:39 +0200
commit407e84cd1e9a802df1955e281d8956439abc499b (patch)
treed9f41bec6fb149ccae1687c6b2cf307f15c19a01 /Documentation/userspace-api/media/v4l/func-mmap.rst
parentmedia: docs: make CEC documents compatible with Sphinx 3.1+ (diff)
downloadlinux-407e84cd1e9a802df1955e281d8956439abc499b.tar.xz
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media: docs: make V4L documents more compatible with Sphinx 3.1+
Sphinx 3.x broke support for the cdomain.py extension, as the c domain code was rewritten. Due to that, the c tags need to be re-written, in order to use the new c domain notation. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Diffstat (limited to 'Documentation/userspace-api/media/v4l/func-mmap.rst')
-rw-r--r--Documentation/userspace-api/media/v4l/func-mmap.rst18
1 files changed, 7 insertions, 11 deletions
diff --git a/Documentation/userspace-api/media/v4l/func-mmap.rst b/Documentation/userspace-api/media/v4l/func-mmap.rst
index b3a9cd862a7f..e3e5e64ebe7e 100644
--- a/Documentation/userspace-api/media/v4l/func-mmap.rst
+++ b/Documentation/userspace-api/media/v4l/func-mmap.rst
@@ -1,4 +1,5 @@
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: V4L
.. _func-mmap:
@@ -11,7 +12,6 @@ Name
v4l2-mmap - Map device memory into application address space
-
Synopsis
========
@@ -20,9 +20,7 @@ Synopsis
#include <unistd.h>
#include <sys/mman.h>
-
.. c:function:: void *mmap( void *start, size_t length, int prot, int flags, int fd, off_t offset )
- :name: v4l2-mmap
Arguments
=========
@@ -54,7 +52,7 @@ Arguments
#. The Linux ``videobuf`` kernel module, which is used by some
drivers supports only ``PROT_READ`` | ``PROT_WRITE``. When the
driver does not support the desired protection, the
- :ref:`mmap() <func-mmap>` function fails.
+ :c:func:`mmap()` function fails.
#. Device memory accesses (e. g. the memory on a graphics card
with video capturing hardware) may incur a performance penalty
@@ -70,7 +68,7 @@ Arguments
``MAP_FIXED`` requests that the driver selects no other address than
the one specified. If the specified address cannot be used,
- :ref:`mmap() <func-mmap>` will fail. If ``MAP_FIXED`` is specified,
+ :c:func:`mmap()` will fail. If ``MAP_FIXED`` is specified,
``start`` must be a multiple of the pagesize. Use of this option is
discouraged.
@@ -87,7 +85,7 @@ Arguments
flags.
``fd``
- File descriptor returned by :ref:`open() <func-open>`.
+ File descriptor returned by :c:func:`open()`.
``offset``
Offset of the buffer in device memory. This must be the same value
@@ -97,11 +95,10 @@ Arguments
in the struct :c:type:`v4l2_plane` ``m`` union
``mem_offset`` field for the multi-planar API.
-
Description
===========
-The :ref:`mmap() <func-mmap>` function asks to map ``length`` bytes starting at
+The :c:func:`mmap()` function asks to map ``length`` bytes starting at
``offset`` in the memory of the device specified by ``fd`` into the
application address space, preferably at address ``start``. This latter
address is a hint only, and is usually specified as 0.
@@ -111,13 +108,12 @@ Suitable length and offset parameters are queried with the
allocated with the :ref:`VIDIOC_REQBUFS` ioctl
before they can be queried.
-To unmap buffers the :ref:`munmap() <func-munmap>` function is used.
-
+To unmap buffers the :c:func:`munmap()` function is used.
Return Value
============
-On success :ref:`mmap() <func-mmap>` returns a pointer to the mapped buffer. On
+On success :c:func:`mmap()` returns a pointer to the mapped buffer. On
error ``MAP_FAILED`` (-1) is returned, and the ``errno`` variable is set
appropriately. Possible error codes are: