75 lines
2.1 KiB
ReStructuredText
75 lines
2.1 KiB
ReStructuredText
.. Permission is granted to copy, distribute and/or modify this
|
|
.. 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/media/uapi/fdl-appendix.rst.
|
|
..
|
|
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
|
|
|
|
.. _media_ioc_setup_link:
|
|
|
|
**************************
|
|
ioctl MEDIA_IOC_SETUP_LINK
|
|
**************************
|
|
|
|
Name
|
|
====
|
|
|
|
MEDIA_IOC_SETUP_LINK - Modify the properties of a link
|
|
|
|
|
|
Synopsis
|
|
========
|
|
|
|
.. c:function:: int ioctl( int fd, MEDIA_IOC_SETUP_LINK, struct media_link_desc *argp )
|
|
:name: MEDIA_IOC_SETUP_LINK
|
|
|
|
|
|
Arguments
|
|
=========
|
|
|
|
``fd``
|
|
File descriptor returned by :ref:`open() <media-func-open>`.
|
|
|
|
``argp``
|
|
Pointer to struct :c:type:`media_link_desc`.
|
|
|
|
|
|
Description
|
|
===========
|
|
|
|
To change link properties applications fill a struct
|
|
:c:type:`media_link_desc` with link identification
|
|
information (source and sink pad) and the new requested link flags. They
|
|
then call the MEDIA_IOC_SETUP_LINK ioctl with a pointer to that
|
|
structure.
|
|
|
|
The only configurable property is the ``ENABLED`` link flag to
|
|
enable/disable a link. Links marked with the ``IMMUTABLE`` link flag can
|
|
not be enabled or disabled.
|
|
|
|
Link configuration has no side effect on other links. If an enabled link
|
|
at the sink pad prevents the link from being enabled, the driver returns
|
|
with an ``EBUSY`` error code.
|
|
|
|
Only links marked with the ``DYNAMIC`` link flag can be enabled/disabled
|
|
while streaming media data. Attempting to enable or disable a streaming
|
|
non-dynamic link will return an ``EBUSY`` error code.
|
|
|
|
If the specified link can't be found the driver returns with an ``EINVAL``
|
|
error code.
|
|
|
|
|
|
Return Value
|
|
============
|
|
|
|
On success 0 is returned, on error -1 and the ``errno`` variable is set
|
|
appropriately. The generic error codes are described at the
|
|
:ref:`Generic Error Codes <gen-errors>` chapter.
|
|
|
|
EINVAL
|
|
The struct :c:type:`media_link_desc` references a
|
|
non-existing link, or the link is immutable and an attempt to modify
|
|
its configuration was made.
|