Merge tag 'media/v4.8-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media

Pull media documentation updates from Mauro Carvalho Chehab:
 "This patch series does the conversion of all media documentation stuff
  to Restrutured Text markup format and add them to the
  Documentation/index.rst file.

  The media documentation was grouped into 4 books:

    - media uAPI
    - media kAPI
    - V4L driver-specific documentation
    - DVB driver-specific documentation

  It also contains several documentation improvements and one fixup
  patch for a core issue with cropcap.

  PS.  After this patch series, the media DocBook is deprecated and
  should be removed.  I'll add such patch on a future pull request"

* tag 'media/v4.8-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (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
  ...

1 files changed, 137 insertions, 0 deletions

diff --git a/Documentation/media/kapi/v4l2-event.rst b/Documentation/media/kapi/v4l2-event.rst
new file mode 100644
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+
+V4L2 events
+-----------
+
+The V4L2 events provide a generic way to pass events to user space.
+The driver must use :c:type:`v4l2_fh` to be able to support V4L2 events.
+
+Events are defined by a type and an optional ID. The ID may refer to a V4L2
+object such as a control ID. If unused, then the ID is 0.
+
+When the user subscribes to an event the driver will allocate a number of
+kevent structs for that event. So every (type, ID) event tuple will have
+its own set of kevent structs. This guarantees that if a driver is generating
+lots of events of one type in a short time, then that will not overwrite
+events of another type.
+
+But if you get more events of one type than the number of kevents that were
+reserved, then the oldest event will be dropped and the new one added.
+
+Furthermore, the internal struct :c:type:`v4l2_subscribed_event` has
+``merge()`` and ``replace()`` callbacks which drivers can set. These
+callbacks are called when a new event is raised and there is no more room.
+The ``replace()`` callback allows you to replace the payload of the old event
+with that of the new event, merging any relevant data from the old payload
+into the new payload that replaces it. It is called when this event type has
+only one kevent struct allocated. The ``merge()`` callback allows you to merge
+the oldest event payload into that of the second-oldest event payload. It is
+called when there are two or more kevent structs allocated.
+
+This way no status information is lost, just the intermediate steps leading
+up to that state.
+
+A good example of these ``replace``/``merge`` callbacks is in v4l2-event.c:
+``ctrls_replace()`` and ``ctrls_merge()`` callbacks for the control event.
+
+.. note::
+	these callbacks can be called from interrupt context, so they must
+	be fast.
+
+In order to queue events to video device, drivers should call:
+
+	:c:func:`v4l2_event_queue <v4l2_event_queue>`
+	(:c:type:`vdev <video_device>`, :ref:`ev <v4l2-event>`)
+
+The driver's only responsibility is to fill in the type and the data fields.
+The other fields will be filled in by V4L2.
+
+Event subscription
+~~~~~~~~~~~~~~~~~~
+
+Subscribing to an event is via:
+
+	:c:func:`v4l2_event_subscribe <v4l2_event_subscribe>`
+	(:c:type:`fh <v4l2_fh>`, :ref:`sub <v4l2-event-subscription>` ,
+	elems, :c:type:`ops <v4l2_subscribed_event_ops>`)
+
+
+This function is used to implement :c:type:`video_device`->
+:c:type:`ioctl_ops <v4l2_ioctl_ops>`-> ``vidioc_subscribe_event``,
+but the driver must check first if the driver is able to produce events
+with specified event id, and then should call
+:c:func:`v4l2_event_subscribe` to subscribe the event.
+
+The elems argument is the size of the event queue for this event. If it is 0,
+then the framework will fill in a default value (this depends on the event
+type).
+
+The ops argument allows the driver to specify a number of callbacks:
+
+======== ==============================================================
+Callback Description
+======== ==============================================================
+add      called when a new listener gets added (subscribing to the same
+         event twice will only cause this callback to get called once)
+del      called when a listener stops listening
+replace  replace event 'old' with event 'new'.
+merge    merge event 'old' into event 'new'.
+======== ==============================================================
+
+All 4 callbacks are optional, if you don't want to specify any callbacks
+the ops argument itself maybe ``NULL``.
+
+Unsubscribing an event
+~~~~~~~~~~~~~~~~~~~~~~
+
+Unsubscribing to an event is via:
+
+	:c:func:`v4l2_event_unsubscribe <v4l2_event_unsubscribe>`
+	(:c:type:`fh <v4l2_fh>`, :ref:`sub <v4l2-event-subscription>`)
+
+This function is used to implement :c:type:`video_device`->
+:c:type:`ioctl_ops <v4l2_ioctl_ops>`-> ``vidioc_unsubscribe_event``.
+A driver may call :c:func:`v4l2_event_unsubscribe` directly unless it
+wants to be involved in unsubscription process.
+
+The special type ``V4L2_EVENT_ALL`` may be used to unsubscribe all events. The
+drivers may want to handle this in a special way.
+
+Check if there's a pending event
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Checking if there's a pending event is via:
+
+	:c:func:`v4l2_event_pending <v4l2_event_pending>`
+	(:c:type:`fh <v4l2_fh>`)
+
+
+This function returns the number of pending events. Useful when implementing
+poll.
+
+How events work
+~~~~~~~~~~~~~~~
+
+Events are delivered to user space through the poll system call. The driver
+can use :c:type:`v4l2_fh`->wait (a wait_queue_head_t) as the argument for
+``poll_wait()``.
+
+There are standard and private events. New standard events must use the
+smallest available event type. The drivers must allocate their events from
+their own class starting from class base. Class base is
+``V4L2_EVENT_PRIVATE_START`` + n * 1000 where n is the lowest available number.
+The first event type in the class is reserved for future use, so the first
+available event type is 'class base + 1'.
+
+An example on how the V4L2 events may be used can be found in the OMAP
+3 ISP driver (``drivers/media/platform/omap3isp``).
+
+A subdev can directly send an event to the :c:type:`v4l2_device` notify
+function with ``V4L2_DEVICE_NOTIFY_EVENT``. This allows the bridge to map
+the subdev that sends the event to the video node(s) associated with the
+subdev that need to be informed about such an event.
+
+V4L2 event functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-event.h
+