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author | Mauro Carvalho Chehab | 2016-07-27 10:45:04 -0300 |
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committer | Mauro Carvalho Chehab | 2016-07-27 10:45:04 -0300 |
commit | 85538b1ad145c67198cb55d02de14ba269cc323d (patch) | |
tree | 409fca93b357839b8c89b7099f2888c087694b64 /Documentation/media/uapi/rc/lirc-read.rst | |
parent | 9c1958fc326a0a0a533ec8e86ea6fa30977207de (diff) | |
parent | d271d3d9b333c94cd54a12fa506e17772a04617c (diff) |
Merge branch 'topic/docs-next' into v4l_for_linus
* topic/docs-next: (322 commits)
[media] cx23885-cardlist.rst: add a new card
[media] doc-rst: add some needed escape codes
[media] doc-rst: kapi: use :c:func: instead of :cpp:func
doc-rst: kernel-doc: fix a change introduced by mistake
[media] v4l2-ioctl.h add debug info for struct v4l2_ioctl_ops
[media] dvb_ringbuffer.h: some documentation improvements
[media] v4l2-ctrls.h: fully document the header file
[media] doc-rst: Fix some typedef ugly warnings
[media] doc-rst: reorganize the kAPI v4l2 chapters
[media] rename v4l2-framework.rst to v4l2-intro.rst
[media] move V4L2 clocks to a separate .rst file
[media] v4l2-fh.rst: add cross references and markups
[media] v4l2-fh.rst: add fh contents from v4l2-framework.rst
[media] v4l2-fh.h: add documentation for it
[media] v4l2-event.rst: add cross-references and markups
[media] v4l2-event.h: document all functions
[media] v4l2-event.rst: add text from v4l2-framework.rst
[media] v4l2-framework.rst: remove videobuf quick chapter
[media] v4l2-dev: add cross-references and improve markup
[media] doc-rst: move v4l2-dev doc to a separate file
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Diffstat (limited to 'Documentation/media/uapi/rc/lirc-read.rst')
-rw-r--r-- | Documentation/media/uapi/rc/lirc-read.rst | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/Documentation/media/uapi/rc/lirc-read.rst b/Documentation/media/uapi/rc/lirc-read.rst new file mode 100644 index 000000000000..8d4e9b6e507d --- /dev/null +++ b/Documentation/media/uapi/rc/lirc-read.rst @@ -0,0 +1,62 @@ +.. -*- coding: utf-8; mode: rst -*- + +.. _lirc-read: + +*********** +LIRC read() +*********** + +Name +==== + +lirc-read - Read from a LIRC device + + +Synopsis +======== + +.. code-block:: c + + #include <unistd.h> + + +.. cpp:function:: ssize_t read( int fd, void *buf, size_t count ) + + +Arguments +========= + +``fd`` + File descriptor returned by ``open()``. + +``buf`` +``count`` + + +Description +=========== + +:ref:`read() <lirc-read>` attempts to read up to ``count`` bytes from file +descriptor ``fd`` into the buffer starting at ``buf``. If ``count`` is zero, +:ref:`read() <lirc-read>` returns zero and has no other results. If ``count`` +is greater than ``SSIZE_MAX``, the result is unspecified. + +The lircd userspace daemon reads raw IR data from the LIRC chardev. The +exact format of the data depends on what modes a driver supports, and +what mode has been selected. lircd obtains supported modes and sets the +active mode via the ioctl interface, detailed at :ref:`lirc_func`. +The generally preferred mode for receive is +:ref:`LIRC_MODE_MODE2 <lirc-mode-mode2>`, in which packets containing an +int value describing an IR signal are read from the chardev. + +See also +`http://www.lirc.org/html/technical.html <http://www.lirc.org/html/technical.html>`__ +for more info. + +Return Value +============ + +On success, the number of bytes read is returned. It is not an error if +this number is smaller than the number of bytes requested, or the amount +of data required for one frame. On error, -1 is returned, and the ``errno`` +variable is set appropriately. |