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-rw-r--r--Documentation/media/uapi/v4l/libv4l-introduction.rst77
1 files changed, 46 insertions, 31 deletions
diff --git a/Documentation/media/uapi/v4l/libv4l-introduction.rst b/Documentation/media/uapi/v4l/libv4l-introduction.rst
index 61d085f9f105..ccc3c4d2fc0f 100644
--- a/Documentation/media/uapi/v4l/libv4l-introduction.rst
+++ b/Documentation/media/uapi/v4l/libv4l-introduction.rst
@@ -113,56 +113,71 @@ Libv4l device control functions
The common file operation methods are provided by libv4l.
-Those functions operate just like glibc
-open/close/dup/ioctl/read/mmap/munmap:
+Those functions operate just like the gcc function ``dup()`` and
+V4L2 functions
+:c:func:`open() <v4l2-open>`, :c:func:`close() <v4l2-close>`,
+:c:func:`ioctl() <v4l2-ioctl>`, :c:func:`read() <v4l2-read>`,
+:c:func:`mmap() <v4l2-mmap>` and :c:func:`munmap() <v4l2-munmap>`:
-- :c:type:`int v4l2_open(const char *file, int oflag, ...)` - operates like the
- standard :ref:`open() <func-open>` function.
+.. c:function:: int v4l2_open(const char *file, int oflag, ...)
-- :c:type:`int v4l2_close(int fd)` - operates like the standard
- :ref:`close() <func-close>` function.
+ operates like the :c:func:`open() <v4l2-open>` function.
-- :c:type:`int v4l2_dup(int fd)` - operates like the standard dup() function,
- duplicating a file handler.
+.. c:function:: int v4l2_close(int fd)
-- :c:type:`int v4l2_ioctl (int fd, unsigned long int request, ...)` - operates
- like the standard :ref:`ioctl() <func-ioctl>` function.
+ operates like the :c:func:`close() <v4l2-close>` function.
-- :c:type:`int v4l2_read (int fd, void* buffer, size_t n)` - operates like the
- standard :ref:`read() <func-read>` function.
+.. c:function:: int v4l2_dup(int fd)
-- :c:type:`void v4l2_mmap(void *start, size_t length, int prot, int flags, int
- fd, int64_t offset);` - operates like the standard
- :ref:`mmap() <func-mmap>` function.
+ operates like the libc ``dup()`` function, duplicating a file handler.
-- :c:type:`int v4l2_munmap(void *_start, size_t length);` - operates like the
- standard :ref:`munmap() <func-munmap>` function.
+.. c:function:: int v4l2_ioctl (int fd, unsigned long int request, ...)
+
+ operates like the :c:func:`ioctl() <v4l2-ioctl>` function.
+
+.. c:function:: int v4l2_read (int fd, void* buffer, size_t n)
+
+ operates like the :c:func:`read() <v4l2-read>` function.
+
+.. c:function:: void v4l2_mmap(void *start, size_t length, int prot, int flags, int fd, int64_t offset);
+
+ operates like the :c:func:`munmap() <v4l2-munmap>` function.
+
+.. c:function:: int v4l2_munmap(void *_start, size_t length);
+
+ operates like the :c:func:`munmap() <v4l2-munmap>` function.
Those functions provide additional control:
-- :c:type:`int v4l2_fd_open(int fd, int v4l2_flags)` - opens an already opened
- fd for further use through v4l2lib and possibly modify libv4l2's
- default behavior through the v4l2_flags argument. Currently,
- v4l2_flags can be ``V4L2_DISABLE_CONVERSION``, to disable format
- conversion.
+.. c:function:: int v4l2_fd_open(int fd, int v4l2_flags)
+
+ opens an already opened fd for further use through v4l2lib and possibly
+ modify libv4l2's default behavior through the ``v4l2_flags`` argument.
+ Currently, ``v4l2_flags`` can be ``V4L2_DISABLE_CONVERSION``, to disable
+ format conversion.
-- :c:type:`int v4l2_set_control(int fd, int cid, int value)` - This function
- takes a value of 0 - 65535, and then scales that range to the actual
- range of the given v4l control id, and then if the cid exists and is
+.. c:function:: int v4l2_set_control(int fd, int cid, int value)
+
+ This function takes a value of 0 - 65535, and then scales that range to the
+ actual range of the given v4l control id, and then if the cid exists and is
not locked sets the cid to the scaled value.
-- :c:type:`int v4l2_get_control(int fd, int cid)` - This function returns a
- value of 0 - 65535, scaled to from the actual range of the given v4l
- control id. when the cid does not exist, could not be accessed for
- some reason, or some error occurred 0 is returned.
+.. c:function:: int v4l2_get_control(int fd, int cid)
+
+ This function returns a value of 0 - 65535, scaled to from the actual range
+ of the given v4l control id. when the cid does not exist, could not be
+ accessed for some reason, or some error occurred 0 is returned.
v4l1compat.so wrapper library
=============================
-This library intercepts calls to open/close/ioctl/mmap/mmunmap
+This library intercepts calls to
+:c:func:`open() <v4l2-open>`, :c:func:`close() <v4l2-close>`,
+:c:func:`ioctl() <v4l2-ioctl>`, :c:func:`mmap() <v4l2-mmap>` and
+:c:func:`munmap() <v4l2-munmap>`
operations and redirects them to the libv4l counterparts, by using
-LD_PRELOAD=/usr/lib/v4l1compat.so. It also emulates V4L1 calls via V4L2
+``LD_PRELOAD=/usr/lib/v4l1compat.so``. It also emulates V4L1 calls via V4L2
API.
It allows usage of binary legacy applications that still don't use