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authorMauro Carvalho Chehab <mchehab@s-opensource.com>2016-07-27 13:45:04 (GMT)
committerMauro Carvalho Chehab <mchehab@s-opensource.com>2016-07-27 13:45:04 (GMT)
commit85538b1ad145c67198cb55d02de14ba269cc323d (patch)
tree409fca93b357839b8c89b7099f2888c087694b64 /Documentation/media/uapi/mediactl/media-ioc-setup-link.rst
parent9c1958fc326a0a0a533ec8e86ea6fa30977207de (diff)
parentd271d3d9b333c94cd54a12fa506e17772a04617c (diff)
downloadlinux-85538b1ad145c67198cb55d02de14ba269cc323d.tar.xz
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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+.. -*- coding: utf-8; mode: rst -*-
+
+.. _media_ioc_setup_link:
+
+**************************
+ioctl MEDIA_IOC_SETUP_LINK
+**************************
+
+Name
+====
+
+MEDIA_IOC_SETUP_LINK - Modify the properties of a link
+
+
+Synopsis
+========
+
+.. cpp:function:: int ioctl( int fd, int request, struct media_link_desc *argp )
+
+
+Arguments
+=========
+
+``fd``
+ File descriptor returned by :ref:`open() <media-func-open>`.
+
+``request``
+ MEDIA_IOC_SETUP_LINK
+
+``argp``
+
+
+Description
+===========
+
+To change link properties applications fill a struct
+:ref:`media_link_desc <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 :ref:`media_link_desc <media-link-desc>` references a
+ non-existing link, or the link is immutable and an attempt to modify
+ its configuration was made.