linux/drivers/media/v4l2-core/v4l2-event.c

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/*
* v4l2-event.c
*
* V4L2 events.
*
* Copyright (C) 2009--2010 Nokia Corporation.
*
* Contact: Sakari Ailus <sakari.ailus@iki.fi>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#include <media/v4l2-dev.h>
#include <media/v4l2-fh.h>
#include <media/v4l2-event.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/export.h>
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
static unsigned sev_pos(const struct v4l2_subscribed_event *sev, unsigned idx)
{
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
idx += sev->first;
return idx >= sev->elems ? idx - sev->elems : idx;
}
static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
{
struct v4l2_kevent *kev;
unsigned long flags;
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
if (list_empty(&fh->available)) {
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
return -ENOENT;
}
WARN_ON(fh->navailable == 0);
kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
list_del(&kev->list);
fh->navailable--;
kev->event.pending = fh->navailable;
*event = kev->event;
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
kev->sev->first = sev_pos(kev->sev, 1);
kev->sev->in_use--;
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
return 0;
}
int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
int nonblocking)
{
int ret;
if (nonblocking)
return __v4l2_event_dequeue(fh, event);
/* Release the vdev lock while waiting */
if (fh->vdev->lock)
mutex_unlock(fh->vdev->lock);
do {
ret = wait_event_interruptible(fh->wait,
fh->navailable != 0);
if (ret < 0)
break;
ret = __v4l2_event_dequeue(fh, event);
} while (ret == -ENOENT);
if (fh->vdev->lock)
mutex_lock(fh->vdev->lock);
return ret;
}
EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
/* Caller must hold fh->vdev->fh_lock! */
static struct v4l2_subscribed_event *v4l2_event_subscribed(
struct v4l2_fh *fh, u32 type, u32 id)
{
struct v4l2_subscribed_event *sev;
assert_spin_locked(&fh->vdev->fh_lock);
list_for_each_entry(sev, &fh->subscribed, list)
if (sev->type == type && sev->id == id)
return sev;
return NULL;
}
static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
const struct timespec *ts)
{
struct v4l2_subscribed_event *sev;
struct v4l2_kevent *kev;
bool copy_payload = true;
/* Are we subscribed? */
sev = v4l2_event_subscribed(fh, ev->type, ev->id);
if (sev == NULL)
return;
/*
* If the event has been added to the fh->subscribed list, but its
* add op has not completed yet elems will be 0, treat this as
* not being subscribed.
*/
if (!sev->elems)
return;
/* Increase event sequence number on fh. */
fh->sequence++;
/* Do we have any free events? */
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
if (sev->in_use == sev->elems) {
/* no, remove the oldest one */
kev = sev->events + sev_pos(sev, 0);
list_del(&kev->list);
sev->in_use--;
sev->first = sev_pos(sev, 1);
fh->navailable--;
if (sev->elems == 1) {
if (sev->ops && sev->ops->replace) {
sev->ops->replace(&kev->event, ev);
copy_payload = false;
}
} else if (sev->ops && sev->ops->merge) {
struct v4l2_kevent *second_oldest =
sev->events + sev_pos(sev, 0);
sev->ops->merge(&kev->event, &second_oldest->event);
}
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
}
/* Take one and fill it. */
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
kev = sev->events + sev_pos(sev, sev->in_use);
kev->event.type = ev->type;
if (copy_payload)
kev->event.u = ev->u;
kev->event.id = ev->id;
kev->event.timestamp = *ts;
kev->event.sequence = fh->sequence;
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
sev->in_use++;
list_add_tail(&kev->list, &fh->available);
fh->navailable++;
wake_up_all(&fh->wait);
}
void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
{
struct v4l2_fh *fh;
unsigned long flags;
struct timespec timestamp;
ktime_get_ts(&timestamp);
spin_lock_irqsave(&vdev->fh_lock, flags);
list_for_each_entry(fh, &vdev->fh_list, list)
__v4l2_event_queue_fh(fh, ev, &timestamp);
spin_unlock_irqrestore(&vdev->fh_lock, flags);
}
EXPORT_SYMBOL_GPL(v4l2_event_queue);
void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
{
unsigned long flags;
struct timespec timestamp;
ktime_get_ts(&timestamp);
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
__v4l2_event_queue_fh(fh, ev, &timestamp);
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
}
EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
int v4l2_event_pending(struct v4l2_fh *fh)
{
return fh->navailable;
}
EXPORT_SYMBOL_GPL(v4l2_event_pending);
int v4l2_event_subscribe(struct v4l2_fh *fh,
const struct v4l2_event_subscription *sub, unsigned elems,
const struct v4l2_subscribed_event_ops *ops)
{
struct v4l2_subscribed_event *sev, *found_ev;
unsigned long flags;
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
unsigned i;
if (sub->type == V4L2_EVENT_ALL)
return -EINVAL;
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
if (elems < 1)
elems = 1;
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
sev = kzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, GFP_KERNEL);
if (!sev)
return -ENOMEM;
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
for (i = 0; i < elems; i++)
sev->events[i].sev = sev;
sev->type = sub->type;
sev->id = sub->id;
sev->flags = sub->flags;
sev->fh = fh;
sev->ops = ops;
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
if (!found_ev)
list_add(&sev->list, &fh->subscribed);
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
if (found_ev) {
kfree(sev);
return 0; /* Already listening */
}
if (sev->ops && sev->ops->add) {
int ret = sev->ops->add(sev, elems);
if (ret) {
sev->ops = NULL;
v4l2_event_unsubscribe(fh, sub);
return ret;
}
}
/* Mark as ready for use */
sev->elems = elems;
return 0;
}
EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
{
struct v4l2_event_subscription sub;
struct v4l2_subscribed_event *sev;
unsigned long flags;
do {
sev = NULL;
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
if (!list_empty(&fh->subscribed)) {
sev = list_first_entry(&fh->subscribed,
struct v4l2_subscribed_event, list);
sub.type = sev->type;
sub.id = sev->id;
}
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
if (sev)
v4l2_event_unsubscribe(fh, &sub);
} while (sev);
}
[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of 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>
2011-06-13 22:24:17 +00:00
EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
int v4l2_event_unsubscribe(struct v4l2_fh *fh,
const struct v4l2_event_subscription *sub)
{
struct v4l2_subscribed_event *sev;
unsigned long flags;
int i;
if (sub->type == V4L2_EVENT_ALL) {
v4l2_event_unsubscribe_all(fh);
return 0;
}
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
sev = v4l2_event_subscribed(fh, sub->type, sub->id);
if (sev != NULL) {
/* Remove any pending events for this subscription */
for (i = 0; i < sev->in_use; i++) {
list_del(&sev->events[sev_pos(sev, i)].list);
fh->navailable--;
}
list_del(&sev->list);
}
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
if (sev && sev->ops && sev->ops->del)
sev->ops->del(sev);
kfree(sev);
return 0;
}
EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
struct v4l2_event_subscription *sub)
{
return v4l2_event_unsubscribe(fh, sub);
}
EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);