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9d4ee1ad92
Several functions weren't documented. Document them all. While here, makes checkpatch.pl happy. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
244 lines
7.7 KiB
C
244 lines
7.7 KiB
C
/*
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* v4l2-event.h
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*
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* V4L2 events.
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*
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* Copyright (C) 2009--2010 Nokia Corporation.
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*
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* Contact: Sakari Ailus <sakari.ailus@iki.fi>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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* 02110-1301 USA
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*/
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#ifndef V4L2_EVENT_H
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#define V4L2_EVENT_H
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#include <linux/types.h>
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#include <linux/videodev2.h>
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#include <linux/wait.h>
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/*
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* Overview:
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*
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* Events are subscribed per-filehandle. An event specification consists of a
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* type and is optionally associated with an object identified through the
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* 'id' field. So an event is uniquely identified by the (type, id) tuple.
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*
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* The v4l2-fh struct has a list of subscribed events. The v4l2_subscribed_event
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* struct is added to that list, one for every subscribed event.
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*
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* Each v4l2_subscribed_event struct ends with an array of v4l2_kevent structs.
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* This array (ringbuffer, really) is used to store any events raised by the
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* driver. The v4l2_kevent struct links into the 'available' list of the
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* v4l2_fh struct so VIDIOC_DQEVENT will know which event to dequeue first.
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*
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* Finally, if the event subscription is associated with a particular object
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* such as a V4L2 control, then that object needs to know about that as well
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* so that an event can be raised by that object. So the 'node' field can
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* be used to link the v4l2_subscribed_event struct into a list of that
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* object.
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*
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* So to summarize:
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*
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* struct v4l2_fh has two lists: one of the subscribed events, and one of the
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* pending events.
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*
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* struct v4l2_subscribed_event has a ringbuffer of raised (pending) events of
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* that particular type.
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*
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* If struct v4l2_subscribed_event is associated with a specific object, then
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* that object will have an internal list of struct v4l2_subscribed_event so
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* it knows who subscribed an event to that object.
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*/
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struct v4l2_fh;
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struct v4l2_subdev;
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struct v4l2_subscribed_event;
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struct video_device;
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/**
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* struct v4l2_kevent - Internal kernel event struct.
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* @list: List node for the v4l2_fh->available list.
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* @sev: Pointer to parent v4l2_subscribed_event.
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* @event: The event itself.
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*/
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struct v4l2_kevent {
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struct list_head list;
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struct v4l2_subscribed_event *sev;
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struct v4l2_event event;
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};
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/**
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* struct v4l2_subscribed_event_ops - Subscribed event operations.
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*
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* @add: Optional callback, called when a new listener is added
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* @del: Optional callback, called when a listener stops listening
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* @replace: Optional callback that can replace event 'old' with event 'new'.
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* @merge: Optional callback that can merge event 'old' into event 'new'.
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*/
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struct v4l2_subscribed_event_ops {
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int (*add)(struct v4l2_subscribed_event *sev, unsigned int elems);
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void (*del)(struct v4l2_subscribed_event *sev);
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void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
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void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
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};
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/**
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* struct v4l2_subscribed_event - Internal struct representing a subscribed
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* event.
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*
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* @list: List node for the v4l2_fh->subscribed list.
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* @type: Event type.
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* @id: Associated object ID (e.g. control ID). 0 if there isn't any.
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* @flags: Copy of v4l2_event_subscription->flags.
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* @fh: Filehandle that subscribed to this event.
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* @node: List node that hooks into the object's event list
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* (if there is one).
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* @ops: v4l2_subscribed_event_ops
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* @elems: The number of elements in the events array.
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* @first: The index of the events containing the oldest available event.
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* @in_use: The number of queued events.
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* @events: An array of @elems events.
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*/
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struct v4l2_subscribed_event {
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struct list_head list;
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u32 type;
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u32 id;
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u32 flags;
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struct v4l2_fh *fh;
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struct list_head node;
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const struct v4l2_subscribed_event_ops *ops;
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unsigned int elems;
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unsigned int first;
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unsigned int in_use;
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struct v4l2_kevent events[];
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};
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/**
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* v4l2_event_dequeue - Dequeue events from video device.
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*
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* @fh: pointer to struct v4l2_fh
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* @event: pointer to struct v4l2_event
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* @nonblocking: if not zero, waits for an event to arrive
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*/
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int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
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int nonblocking);
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/**
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* v4l2_event_queue - Queue events to video device.
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*
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* @vdev: pointer to &struct video_device
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* @ev: pointer to &struct v4l2_event
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*
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* The event will be queued for all &struct v4l2_fh file handlers.
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*
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* .. note::
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* The driver's only responsibility is to fill in the type and the data
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* fields.The other fields will be filled in by V4L2.
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*/
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void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
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/**
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* v4l2_event_queue_fh - Queue events to video device.
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*
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* @fh: pointer to &struct v4l2_fh
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* @ev: pointer to &struct v4l2_event
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*
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*
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* The event will be queued only for the specified &struct v4l2_fh file handler.
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*
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* .. note::
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* The driver's only responsibility is to fill in the type and the data
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* fields.The other fields will be filled in by V4L2.
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*/
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void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
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/**
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* v4l2_event_pending - Check if an event is available
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*
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* @fh: pointer to &struct v4l2_fh
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*
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* Returns the number of pending events.
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*/
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int v4l2_event_pending(struct v4l2_fh *fh);
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/**
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* v4l2_event_subscribe - Subscribes to an event
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*
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* @fh: pointer to &struct v4l2_fh
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* @sub: pointer to &struct v4l2_event_subscription
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* @elems: size of the events queue
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* @ops: pointer to &v4l2_subscribed_event_ops
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*
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* .. note::
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*
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* if @elems is zero, the framework will fill in a default value,
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* with is currently 1 element.
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*/
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int v4l2_event_subscribe(struct v4l2_fh *fh,
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const struct v4l2_event_subscription *sub,
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unsigned int elems,
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const struct v4l2_subscribed_event_ops *ops);
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/**
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* v4l2_event_unsubscribe - Unsubscribes to an event
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*
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* @fh: pointer to &struct v4l2_fh
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* @sub: pointer to &struct v4l2_event_subscription
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*/
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int v4l2_event_unsubscribe(struct v4l2_fh *fh,
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const struct v4l2_event_subscription *sub);
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/**
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* v4l2_event_unsubscribe_all - Unsubscribes to all events
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*
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* @fh: pointer to &struct v4l2_fh
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*/
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void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
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/**
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* v4l2_event_subdev_unsubscribe - Subdev variant of v4l2_event_unsubscribe()
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*
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* @sd: pointer to &struct v4l2_subdev
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* @fh: pointer to &struct v4l2_fh
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* @sub: pointer to &struct v4l2_event_subscription
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*
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* .. note::
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*
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* This function should be used for the &struct v4l2_subdev_core_ops
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* %unsubscribe_event field.
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*/
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int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd,
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struct v4l2_fh *fh,
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struct v4l2_event_subscription *sub);
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/**
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* v4l2_src_change_event_subscribe -
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*
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* @fh: pointer to struct v4l2_fh
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* @sub: pointer to &struct v4l2_event_subscription
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*/
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int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
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const struct v4l2_event_subscription *sub);
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/**
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* v4l2_src_change_event_subdev_subscribe - Variant of v4l2_event_subscribe(),
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* meant to subscribe only events of the type %V4L2_EVENT_SOURCE_CHANGE.
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*
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* @sd: pointer to &struct v4l2_subdev
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* @fh: pointer to &struct v4l2_fh
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* @sub: pointer to &struct v4l2_event_subscription
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*/
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int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
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struct v4l2_fh *fh,
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struct v4l2_event_subscription *sub);
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#endif /* V4L2_EVENT_H */
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