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Diffstat (limited to 'Documentation/media/uapi/v4l/vidioc-subscribe-event.rst')
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diff --git a/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst b/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst deleted file mode 100644 index a2d3454555ba..000000000000 --- a/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst +++ /dev/null @@ -1,123 +0,0 @@ -.. 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 - -.. _VIDIOC_SUBSCRIBE_EVENT: -.. _VIDIOC_UNSUBSCRIBE_EVENT: - -****************************************************** -ioctl VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT -****************************************************** - -Name -==== - -VIDIOC_SUBSCRIBE_EVENT - VIDIOC_UNSUBSCRIBE_EVENT - Subscribe or unsubscribe event - - -Synopsis -======== - -.. c:function:: int ioctl( int fd, VIDIOC_SUBSCRIBE_EVENT, struct v4l2_event_subscription *argp ) - :name: VIDIOC_SUBSCRIBE_EVENT - -.. c:function:: int ioctl( int fd, VIDIOC_UNSUBSCRIBE_EVENT, struct v4l2_event_subscription *argp ) - :name: VIDIOC_UNSUBSCRIBE_EVENT - - -Arguments -========= - -``fd`` - File descriptor returned by :ref:`open() <func-open>`. - -``argp`` - Pointer to struct :c:type:`v4l2_event_subscription`. - - -Description -=========== - -Subscribe or unsubscribe V4L2 event. Subscribed events are dequeued by -using the :ref:`VIDIOC_DQEVENT` ioctl. - - -.. tabularcolumns:: |p{4.6cm}|p{4.4cm}|p{8.7cm}| - -.. c:type:: v4l2_event_subscription - -.. flat-table:: struct v4l2_event_subscription - :header-rows: 0 - :stub-columns: 0 - :widths: 1 1 2 - - * - __u32 - - ``type`` - - Type of the event, see :ref:`event-type`. - - .. note:: - - ``V4L2_EVENT_ALL`` can be used with - :ref:`VIDIOC_UNSUBSCRIBE_EVENT <VIDIOC_SUBSCRIBE_EVENT>` for - unsubscribing all events at once. - * - __u32 - - ``id`` - - ID of the event source. If there is no ID associated with the - event source, then set this to 0. Whether or not an event needs an - ID depends on the event type. - * - __u32 - - ``flags`` - - Event flags, see :ref:`event-flags`. - * - __u32 - - ``reserved``\ [5] - - Reserved for future extensions. Drivers and applications must set - the array to zero. - - - -.. tabularcolumns:: |p{6.8cm}|p{2.2cm}|p{8.5cm}| - -.. _event-flags: - -.. flat-table:: Event Flags - :header-rows: 0 - :stub-columns: 0 - :widths: 3 1 4 - - * - ``V4L2_EVENT_SUB_FL_SEND_INITIAL`` - - 0x0001 - - When this event is subscribed an initial event will be sent - containing the current status. This only makes sense for events - that are triggered by a status change such as ``V4L2_EVENT_CTRL``. - Other events will ignore this flag. - * - ``V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK`` - - 0x0002 - - If set, then events directly caused by an ioctl will also be sent - to the filehandle that called that ioctl. For example, changing a - control using :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` will cause - a V4L2_EVENT_CTRL to be sent back to that same filehandle. - Normally such events are suppressed to prevent feedback loops - where an application changes a control to a one value and then - another, and then receives an event telling it that that control - has changed to the first value. - - Since it can't tell whether that event was caused by another - application or by the :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` - call it is hard to decide whether to set the control to the value - in the event, or ignore it. - - Think carefully when you set this flag so you won't get into - situations like that. - - -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. |