54f38fcae5
Since 2017, there is an space reserved for userspace API,
created by changeset 1d596dee38 ("docs: Create a user-space API guide").
As the media subsystem was one of the first subsystems to use
Sphinx, until this patch, we were keeping things on a separate
place.
Let's just use the new location, as having all uAPI altogether
will likely make things easier for developers.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
115 lines
2.8 KiB
ReStructuredText
115 lines
2.8 KiB
ReStructuredText
.. Permission is granted to copy, distribute and/or modify this
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.. document under the terms of the GNU Free Documentation License,
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.. Version 1.1 or any later version published by the Free Software
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.. Foundation, with no Invariant Sections, no Front-Cover Texts
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.. and no Back-Cover Texts. A copy of the license is included at
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.. Documentation/userspace-api/media/fdl-appendix.rst.
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..
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.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
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.. _VIDEO_GET_EVENT:
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===============
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VIDEO_GET_EVENT
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===============
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Name
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----
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VIDEO_GET_EVENT
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.. attention:: This ioctl is deprecated.
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Synopsis
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--------
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.. c:function:: int ioctl(fd, VIDEO_GET_EVENT, struct video_event *ev)
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:name: VIDEO_GET_EVENT
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Arguments
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---------
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.. flat-table::
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:header-rows: 0
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:stub-columns: 0
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- .. row 1
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- int fd
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- File descriptor returned by a previous call to open().
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- .. row 2
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- int request
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- Equals VIDEO_GET_EVENT for this command.
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- .. row 3
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- struct video_event \*ev
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- Points to the location where the event, if any, is to be stored.
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Description
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-----------
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This ioctl is for Digital TV devices only. To get events from a V4L2 decoder
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use the V4L2 :ref:`VIDIOC_DQEVENT` ioctl instead.
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This ioctl call returns an event of type video_event if available. If
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an event is not available, the behavior depends on whether the device is
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in blocking or non-blocking mode. In the latter case, the call fails
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immediately with errno set to ``EWOULDBLOCK``. In the former case, the call
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blocks until an event becomes available. The standard Linux poll()
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and/or select() system calls can be used with the device file descriptor
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to watch for new events. For select(), the file descriptor should be
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included in the exceptfds argument, and for poll(), POLLPRI should be
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specified as the wake-up condition. Read-only permissions are sufficient
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for this ioctl call.
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.. c:type:: video_event
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.. code-block:: c
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struct video_event {
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__s32 type;
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#define VIDEO_EVENT_SIZE_CHANGED 1
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#define VIDEO_EVENT_FRAME_RATE_CHANGED 2
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#define VIDEO_EVENT_DECODER_STOPPED 3
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#define VIDEO_EVENT_VSYNC 4
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long timestamp;
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union {
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video_size_t size;
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unsigned int frame_rate; /* in frames per 1000sec */
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unsigned char vsync_field; /* unknown/odd/even/progressive */
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} u;
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};
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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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.. flat-table::
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:header-rows: 0
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:stub-columns: 0
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- .. row 1
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- ``EWOULDBLOCK``
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- There is no event pending, and the device is in non-blocking mode.
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- .. row 2
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- ``EOVERFLOW``
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- Overflow in event queue - one or more events were lost.
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