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