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path: root/include/media/v4l2-event.h
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2011-07-27[media] v4l2-event.h: add overview documentation to the headerHans Verkuil
It's getting confusing who is linking to what, so add an overview at the start of the header. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27[media] v4l2-ctrls/v4l2-events: small coding style cleanupsHans Verkuil
Thanks to Laurent Pinchart <laurent.pinchart@ideasonboard.com>. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27[media] v4l2-event: add optional merge and replace callbacksHans Verkuil
When the event queue for a subscribed event is full, then the oldest event is dropped. It would be nice if the contents of that oldest event could be merged with the next-oldest. That way no information is lost, only intermediate steps are lost. This patch adds optional replace() (called when only one kevent was allocated) and merge() (called when more than one kevent was allocated) callbacks that will be called to do this job. These two callbacks are implemented for the V4L2_EVENT_CTRL event. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of ↵Hans Verkuil
just per-fh The driver had to decide how many events to allocate when the v4l2_fh struct was created. It was possible to add more events afterwards, but there was no way to ensure that you wouldn't miss important events if the event queue would fill up for that filehandle. In addition, once there were no more free events, any new events were simply dropped on the floor. For the control event in particular this made life very difficult since control status/value changes could just be missed if the number of allocated events and the speed at which the application read events was too low to keep up with the number of generated events. The application would have no idea what the latest state was for a control since it could have missed the latest control change. So this patch makes some major changes in how events are allocated. Instead of allocating events per-filehandle they are now allocated when subscribing an event. So for that particular event type N events (determined by the driver) are allocated. Those events are reserved for that particular event type. This ensures that you will not miss events for a particular type altogether. In addition, if there are N events in use and a new event is raised, then the oldest event is dropped and the new one is added. So the latest event is always available. This can be further improved by adding the ability to merge the state of two events together, ensuring that no data is lost at all. This will be added in the next patch. This also makes it possible to allow the user to determine the number of events that will be allocated. This is not implemented at the moment, but would be trivial. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27[media] v4l2-ctrls/event: remove struct v4l2_ctrl_fh, instead use ↵Hans Verkuil
v4l2_subscribed_event The v4l2_ctrl_fh struct connected v4l2_ctrl with v4l2_fh so the control would know which filehandles subscribed to it. However, it is much easier to use struct v4l2_subscribed_event directly for that and get rid of that intermediate struct. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27[media] v4l2-events/fh: merge v4l2_events into v4l2_fhHans Verkuil
Drivers that supported events used to be rare, but now that controls can also raise events this will become much more common since almost all drivers have controls. This means that keeping struct v4l2_events as a separate struct make no more sense. Merging it into struct v4l2_fh simplifies things substantially as it is now an integral part of the filehandle struct. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27[media] v4l2-ctrls: add control eventsHans Verkuil
Whenever a control changes value or state an event is sent to anyone that subscribed to it. This functionality is useful for control panels but also for applications that need to wait for (usually status) controls to change value. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2010-05-19V4L/DVB: V4L: Events: Add backendSakari Ailus
Add event handling backend to V4L2. The backend handles event subscription and delivery to file handles. Event subscriptions are based on file handle. Events may be delivered to all subscribed file handles on a device independent of where they originate from. Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>