linux/Documentation/media/uapi/dvb/ca-get-msg.rst
Mauro Carvalho Chehab 7e6854a9bf media: ca.h: document ca_msg and the corresponding ioctls
Usually, CA messages are sent/received via reading/writing at
the CA device node. However, two drivers (dst_ca and firedtv-ci)
also implement it via ioctls.

Apparently, on both cases, the net result is the same.

Anyway, let's document it.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2017-09-05 06:23:28 -04:00

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.. -*- coding: utf-8; mode: rst -*-
.. _CA_GET_MSG:
==========
CA_GET_MSG
==========
Name
----
CA_GET_MSG
Synopsis
--------
.. c:function:: int ioctl(fd, CA_GET_MSG, struct ca_msg *msg)
:name: CA_GET_MSG
Arguments
---------
``fd``
File descriptor returned by a previous call to :c:func:`open() <dvb-ca-open>`.
``msg``
Pointer to struct :c:type:`ca_msg`.
Description
-----------
Receives a message via a CI CA module.
.. note::
Please notice that, on most drivers, this is done by reading from
the /dev/adapter?/ca? device node.
Return Value
------------
On success 0 is returned.
On error -1 is returned, and the ``errno`` variable is set
appropriately.
Generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.