doc-rst: linux_tv DocBook to reST migration (docs-next)
This is the restructuredText (reST) migration of the ``media``
DocBook-XML set from the linux_tv project.
Signed-off-by: Markus Heiser <markus.heiser@darmarIT.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
diff --git a/Documentation/linux_tv/media/v4l/vidioc-dqevent.rst b/Documentation/linux_tv/media/v4l/vidioc-dqevent.rst
new file mode 100644
index 0000000..108348e
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+.. -*- coding: utf-8; mode: rst -*-
+
+.. _vidioc-dqevent:
+
+********************
+ioctl VIDIOC_DQEVENT
+********************
+
+*man VIDIOC_DQEVENT(2)*
+
+Dequeue event
+
+
+Synopsis
+========
+
+.. c:function:: int ioctl( int fd, int request, struct v4l2_event *argp )
+
+Arguments
+=========
+
+``fd``
+ File descriptor returned by :ref:`open() <func-open>`.
+
+``request``
+ VIDIOC_DQEVENT
+
+``argp``
+
+
+Description
+===========
+
+Dequeue an event from a video device. No input is required for this
+ioctl. All the fields of the struct :ref:`v4l2_event <v4l2-event>`
+structure are filled by the driver. The file handle will also receive
+exceptions which the application may get by e.g. using the select system
+call.
+
+
+.. _v4l2-event:
+
+.. flat-table:: struct v4l2_event
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 1 1 2 1
+
+
+ - .. row 1
+
+ - __u32
+
+ - ``type``
+
+ -
+ - Type of the event, see :ref:`event-type`.
+
+ - .. row 2
+
+ - union
+
+ - ``u``
+
+ -
+ -
+
+ - .. row 3
+
+ -
+ - struct :ref:`v4l2_event_vsync <v4l2-event-vsync>`
+
+ - ``vsync``
+
+ - Event data for event ``V4L2_EVENT_VSYNC``.
+
+ - .. row 4
+
+ -
+ - struct :ref:`v4l2_event_ctrl <v4l2-event-ctrl>`
+
+ - ``ctrl``
+
+ - Event data for event ``V4L2_EVENT_CTRL``.
+
+ - .. row 5
+
+ -
+ - struct :ref:`v4l2_event_frame_sync <v4l2-event-frame-sync>`
+
+ - ``frame_sync``
+
+ - Event data for event ``V4L2_EVENT_FRAME_SYNC``.
+
+ - .. row 6
+
+ -
+ - struct :ref:`v4l2_event_motion_det <v4l2-event-motion-det>`
+
+ - ``motion_det``
+
+ - Event data for event V4L2_EVENT_MOTION_DET.
+
+ - .. row 7
+
+ -
+ - struct :ref:`v4l2_event_src_change <v4l2-event-src-change>`
+
+ - ``src_change``
+
+ - Event data for event V4L2_EVENT_SOURCE_CHANGE.
+
+ - .. row 8
+
+ -
+ - __u8
+
+ - ``data``\ [64]
+
+ - Event data. Defined by the event type. The union should be used to
+ define easily accessible type for events.
+
+ - .. row 9
+
+ - __u32
+
+ - ``pending``
+
+ -
+ - Number of pending events excluding this one.
+
+ - .. row 10
+
+ - __u32
+
+ - ``sequence``
+
+ -
+ - Event sequence number. The sequence number is incremented for
+ every subscribed event that takes place. If sequence numbers are
+ not contiguous it means that events have been lost.
+
+ - .. row 11
+
+ - struct timespec
+
+ - ``timestamp``
+
+ -
+ - Event timestamp. The timestamp has been taken from the
+ ``CLOCK_MONOTONIC`` clock. To access the same clock outside V4L2,
+ use :c:func:`clock_gettime(2)`.
+
+ - .. row 12
+
+ - u32
+
+ - ``id``
+
+ -
+ - The ID associated with the event source. If the event does not
+ have an associated ID (this depends on the event type), then this
+ is 0.
+
+ - .. row 13
+
+ - __u32
+
+ - ``reserved``\ [8]
+
+ -
+ - Reserved for future extensions. Drivers must set the array to
+ zero.
+
+
+
+.. _event-type:
+
+.. flat-table:: Event Types
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 3 1 4
+
+
+ - .. row 1
+
+ - ``V4L2_EVENT_ALL``
+
+ - 0
+
+ - All events. V4L2_EVENT_ALL is valid only for
+ VIDIOC_UNSUBSCRIBE_EVENT for unsubscribing all events at once.
+
+ - .. row 2
+
+ - ``V4L2_EVENT_VSYNC``
+
+ - 1
+
+ - This event is triggered on the vertical sync. This event has a
+ struct :ref:`v4l2_event_vsync <v4l2-event-vsync>` associated
+ with it.
+
+ - .. row 3
+
+ - ``V4L2_EVENT_EOS``
+
+ - 2
+
+ - This event is triggered when the end of a stream is reached. This
+ is typically used with MPEG decoders to report to the application
+ when the last of the MPEG stream has been decoded.
+
+ - .. row 4
+
+ - ``V4L2_EVENT_CTRL``
+
+ - 3
+
+ - This event requires that the ``id`` matches the control ID from
+ which you want to receive events. This event is triggered if the
+ control's value changes, if a button control is pressed or if the
+ control's flags change. This event has a struct
+ :ref:`v4l2_event_ctrl <v4l2-event-ctrl>` associated with it.
+ This struct contains much of the same information as struct
+ :ref:`v4l2_queryctrl <v4l2-queryctrl>` and struct
+ :ref:`v4l2_control <v4l2-control>`.
+
+ If the event is generated due to a call to
+ :ref:`VIDIOC_S_CTRL <vidioc-g-ctrl>` or
+ :ref:`VIDIOC_S_EXT_CTRLS <vidioc-g-ext-ctrls>`, then the
+ event will *not* be sent to the file handle that called the ioctl
+ function. This prevents nasty feedback loops. If you *do* want to
+ get the event, then set the ``V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK``
+ flag.
+
+ This event type will ensure that no information is lost when more
+ events are raised than there is room internally. In that case the
+ struct :ref:`v4l2_event_ctrl <v4l2-event-ctrl>` of the
+ second-oldest event is kept, but the ``changes`` field of the
+ second-oldest event is ORed with the ``changes`` field of the
+ oldest event.
+
+ - .. row 5
+
+ - ``V4L2_EVENT_FRAME_SYNC``
+
+ - 4
+
+ - Triggered immediately when the reception of a frame has begun.
+ This event has a struct
+ :ref:`v4l2_event_frame_sync <v4l2-event-frame-sync>`
+ associated with it.
+
+ If the hardware needs to be stopped in the case of a buffer
+ underrun it might not be able to generate this event. In such
+ cases the ``frame_sequence`` field in struct
+ :ref:`v4l2_event_frame_sync <v4l2-event-frame-sync>` will not
+ be incremented. This causes two consecutive frame sequence numbers
+ to have n times frame interval in between them.
+
+ - .. row 6
+
+ - ``V4L2_EVENT_SOURCE_CHANGE``
+
+ - 5
+
+ - This event is triggered when a source parameter change is detected
+ during runtime by the video device. It can be a runtime resolution
+ change triggered by a video decoder or the format change happening
+ on an input connector. This event requires that the ``id`` matches
+ the input index (when used with a video device node) or the pad
+ index (when used with a subdevice node) from which you want to
+ receive events.
+
+ This event has a struct
+ :ref:`v4l2_event_src_change <v4l2-event-src-change>`
+ associated with it. The ``changes`` bitfield denotes what has
+ changed for the subscribed pad. If multiple events occurred before
+ application could dequeue them, then the changes will have the
+ ORed value of all the events generated.
+
+ - .. row 7
+
+ - ``V4L2_EVENT_MOTION_DET``
+
+ - 6
+
+ - Triggered whenever the motion detection state for one or more of
+ the regions changes. This event has a struct
+ :ref:`v4l2_event_motion_det <v4l2-event-motion-det>`
+ associated with it.
+
+ - .. row 8
+
+ - ``V4L2_EVENT_PRIVATE_START``
+
+ - 0x08000000
+
+ - Base event number for driver-private events.
+
+
+
+.. _v4l2-event-vsync:
+
+.. flat-table:: struct v4l2_event_vsync
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 1 1 2
+
+
+ - .. row 1
+
+ - __u8
+
+ - ``field``
+
+ - The upcoming field. See enum :ref:`v4l2_field <v4l2-field>`.
+
+
+
+.. _v4l2-event-ctrl:
+
+.. flat-table:: struct v4l2_event_ctrl
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 1 1 2 1
+
+
+ - .. row 1
+
+ - __u32
+
+ - ``changes``
+
+ -
+ - A bitmask that tells what has changed. See
+ :ref:`ctrl-changes-flags`.
+
+ - .. row 2
+
+ - __u32
+
+ - ``type``
+
+ -
+ - The type of the control. See enum
+ :ref:`v4l2_ctrl_type <v4l2-ctrl-type>`.
+
+ - .. row 3
+
+ - union (anonymous)
+
+ -
+ -
+ -
+
+ - .. row 4
+
+ -
+ - __s32
+
+ - ``value``
+
+ - The 32-bit value of the control for 32-bit control types. This is
+ 0 for string controls since the value of a string cannot be passed
+ using :ref:`VIDIOC_DQEVENT <vidioc-dqevent>`.
+
+ - .. row 5
+
+ -
+ - __s64
+
+ - ``value64``
+
+ - The 64-bit value of the control for 64-bit control types.
+
+ - .. row 6
+
+ - __u32
+
+ - ``flags``
+
+ -
+ - The control flags. See :ref:`control-flags`.
+
+ - .. row 7
+
+ - __s32
+
+ - ``minimum``
+
+ -
+ - The minimum value of the control. See struct
+ :ref:`v4l2_queryctrl <v4l2-queryctrl>`.
+
+ - .. row 8
+
+ - __s32
+
+ - ``maximum``
+
+ -
+ - The maximum value of the control. See struct
+ :ref:`v4l2_queryctrl <v4l2-queryctrl>`.
+
+ - .. row 9
+
+ - __s32
+
+ - ``step``
+
+ -
+ - The step value of the control. See struct
+ :ref:`v4l2_queryctrl <v4l2-queryctrl>`.
+
+ - .. row 10
+
+ - __s32
+
+ - ``default_value``
+
+ -
+ - The default value value of the control. See struct
+ :ref:`v4l2_queryctrl <v4l2-queryctrl>`.
+
+
+
+.. _v4l2-event-frame-sync:
+
+.. flat-table:: struct v4l2_event_frame_sync
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 1 1 2
+
+
+ - .. row 1
+
+ - __u32
+
+ - ``frame_sequence``
+
+ - The sequence number of the frame being received.
+
+
+
+.. _v4l2-event-src-change:
+
+.. flat-table:: struct v4l2_event_src_change
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 1 1 2
+
+
+ - .. row 1
+
+ - __u32
+
+ - ``changes``
+
+ - A bitmask that tells what has changed. See
+ :ref:`src-changes-flags`.
+
+
+
+.. _v4l2-event-motion-det:
+
+.. flat-table:: struct v4l2_event_motion_det
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 1 1 2
+
+
+ - .. row 1
+
+ - __u32
+
+ - ``flags``
+
+ - Currently only one flag is available: if
+ ``V4L2_EVENT_MD_FL_HAVE_FRAME_SEQ`` is set, then the
+ ``frame_sequence`` field is valid, otherwise that field should be
+ ignored.
+
+ - .. row 2
+
+ - __u32
+
+ - ``frame_sequence``
+
+ - The sequence number of the frame being received. Only valid if the
+ ``V4L2_EVENT_MD_FL_HAVE_FRAME_SEQ`` flag was set.
+
+ - .. row 3
+
+ - __u32
+
+ - ``region_mask``
+
+ - The bitmask of the regions that reported motion. There is at least
+ one region. If this field is 0, then no motion was detected at
+ all. If there is no ``V4L2_CID_DETECT_MD_REGION_GRID`` control
+ (see :ref:`detect-controls`) to assign a different region to
+ each cell in the motion detection grid, then that all cells are
+ automatically assigned to the default region 0.
+
+
+
+.. _ctrl-changes-flags:
+
+.. flat-table:: Control Changes
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 3 1 4
+
+
+ - .. row 1
+
+ - ``V4L2_EVENT_CTRL_CH_VALUE``
+
+ - 0x0001
+
+ - This control event was triggered because the value of the control
+ changed. Special cases: Volatile controls do no generate this
+ event; If a control has the ``V4L2_CTRL_FLAG_EXECUTE_ON_WRITE``
+ flag set, then this event is sent as well, regardless its value.
+
+ - .. row 2
+
+ - ``V4L2_EVENT_CTRL_CH_FLAGS``
+
+ - 0x0002
+
+ - This control event was triggered because the control flags
+ changed.
+
+ - .. row 3
+
+ - ``V4L2_EVENT_CTRL_CH_RANGE``
+
+ - 0x0004
+
+ - This control event was triggered because the minimum, maximum,
+ step or the default value of the control changed.
+
+
+
+.. _src-changes-flags:
+
+.. flat-table:: Source Changes
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 3 1 4
+
+
+ - .. row 1
+
+ - ``V4L2_EVENT_SRC_CH_RESOLUTION``
+
+ - 0x0001
+
+ - This event gets triggered when a resolution change is detected at
+ an input. This can come from an input connector or from a video
+ decoder.
+
+
+
+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.
+
+
+.. ------------------------------------------------------------------------------
+.. This file was automatically converted from DocBook-XML with the dbxml
+.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
+.. from the linux kernel, refer to:
+..
+.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
+.. ------------------------------------------------------------------------------