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- .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
- .. c:namespace:: MC
- .. _media_ioc_setup_link:
- **************************
- ioctl MEDIA_IOC_SETUP_LINK
- **************************
- Name
- ====
- MEDIA_IOC_SETUP_LINK - Modify the properties of a link
- Synopsis
- ========
- .. c:macro:: MEDIA_IOC_SETUP_LINK
- ``int ioctl(int fd, MEDIA_IOC_SETUP_LINK, struct media_link_desc *argp)``
- Arguments
- =========
- ``fd``
- File descriptor returned by :c: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.
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