[PATCH 03/10] v4l2-event: Add v4l2_subscribed_event_ops

Hans de Goede
2012-03-25T11:54:53Z

Just like with ctrl events, drivers may want to get called back on
listener add / remove for other event types too. Rather then special
casing all of this in subscribe / unsubscribe event it is better to
use ops for this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
---
Documentation/video4linux/v4l2-framework.txt | 28 +++++++++----
drivers/media/video/ivtv/ivtv-ioctl.c | 2 +-
drivers/media/video/omap3isp/ispccdc.c | 2 +-
drivers/media/video/omap3isp/ispstat.c | 2 +-
drivers/media/video/v4l2-ctrls.c | 2 +-
drivers/media/video/v4l2-event.c | 54 ++++++++++++++++++++------
drivers/usb/gadget/uvc_v4l2.c | 2 +-
include/media/v4l2-event.h | 24 ++++++++----
8 files changed, 86 insertions(+), 30 deletions(-)

diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 659b2ba..b77bb48 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -941,21 +941,35 @@ fast.

Useful functions:

-- v4l2_event_queue()
+void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)

Queue events to video device. The driver's only responsibility is to fill
in the type and the data fields. The other fields will be filled in by
V4L2.

-- v4l2_event_subscribe()
+int v4l2_event_subscribe(struct v4l2_fh *fh,
+ struct v4l2_event_subscription *sub, unsigned elems,
+ const struct v4l2_subscribed_event_ops *ops)

The video_device->ioctl_ops->vidioc_subscribe_event must check the driver
is able to produce events with specified event id. Then it calls
- v4l2_event_subscribe() to subscribe the event. The last 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).
+ v4l2_event_subscribe() to subscribe the event.

-- v4l2_event_unsubscribe()
+ 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:
+ * 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.
+
+int v4l2_event_unsubscribe(struct v4l2_fh *fh,
+ struct v4l2_event_subscription *sub)

vidioc_unsubscribe_event in struct v4l2_ioctl_ops. A driver may use
v4l2_event_unsubscribe() directly unless it wants to be involved in
@@ -964,7 +978,7 @@ Useful functions:
The special type V4L2_EVENT_ALL may be used to unsubscribe all events. The
drivers may want to handle this in a special way.

-- v4l2_event_pending()
+int v4l2_event_pending(struct v4l2_fh *fh)

Returns the number of pending events. Useful when implementing poll.

diff --git a/drivers/media/video/ivtv/ivtv-ioctl.c b/drivers/media/video/ivtv/ivtv-ioctl.c
index 5452bee..5b41e5b 100644
--- a/drivers/media/video/ivtv/ivtv-ioctl.c
+++ b/drivers/media/video/ivtv/ivtv-ioctl.c
@@ -1469,7 +1469,7 @@ static int ivtv_subscribe_event(struct v4l2_fh *fh, struct v4l2_event_subscripti
case V4L2_EVENT_VSYNC:
case V4L2_EVENT_EOS:
case V4L2_EVENT_CTRL:
- return v4l2_event_subscribe(fh, sub, 0);
+ return v4l2_event_subscribe(fh, sub, 0, NULL);
default:
return -EINVAL;
}
diff --git a/drivers/media/video/omap3isp/ispccdc.c b/drivers/media/video/omap3isp/ispccdc.c
index eaabc27..1f3c16d 100644
--- a/drivers/media/video/omap3isp/ispccdc.c
+++ b/drivers/media/video/omap3isp/ispccdc.c
@@ -1703,7 +1703,7 @@ static int ccdc_subscribe_event(struct v4l2_subdev *sd, struct v4l2_fh *fh,
if (sub->id != 0)
return -EINVAL;

- return v4l2_event_subscribe(fh, sub, OMAP3ISP_CCDC_NEVENTS);
+ return v4l2_event_subscribe(fh, sub, OMAP3ISP_CCDC_NEVENTS, NULL);
}

static int ccdc_unsubscribe_event(struct v4l2_subdev *sd, struct v4l2_fh *fh,
diff --git a/drivers/media/video/omap3isp/ispstat.c b/drivers/media/video/omap3isp/ispstat.c
index 11871ec..b8640be 100644
--- a/drivers/media/video/omap3isp/ispstat.c
+++ b/drivers/media/video/omap3isp/ispstat.c
@@ -1032,7 +1032,7 @@ int omap3isp_stat_subscribe_event(struct v4l2_subdev *subdev,
if (sub->type != stat->event_type)
return -EINVAL;

- return v4l2_event_subscribe(fh, sub, STAT_NEVENTS);
+ return v4l2_event_subscribe(fh, sub, STAT_NEVENTS, NULL);
}

int omap3isp_stat_unsubscribe_event(struct v4l2_subdev *subdev,
diff --git a/drivers/media/video/v4l2-ctrls.c b/drivers/media/video/v4l2-ctrls.c
index 18015c0..7023e6d 100644
--- a/drivers/media/video/v4l2-ctrls.c
+++ b/drivers/media/video/v4l2-ctrls.c
@@ -2425,7 +2425,7 @@ int v4l2_ctrl_subscribe_event(struct v4l2_fh *fh,
struct v4l2_event_subscription *sub)
{
if (sub->type == V4L2_EVENT_CTRL)
- return v4l2_event_subscribe(fh, sub, 0);
+ return v4l2_event_subscribe(fh, sub, 0, NULL);
return -EINVAL;
}
EXPORT_SYMBOL(v4l2_ctrl_subscribe_event);
diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
index c26ad96..0ba2dfa 100644
--- a/drivers/media/video/v4l2-event.c
+++ b/drivers/media/video/v4l2-event.c
@@ -120,6 +120,14 @@ static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *e
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++;

@@ -132,14 +140,14 @@ static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *e
sev->first = sev_pos(sev, 1);
fh->navailable--;
if (sev->elems == 1) {
- if (sev->replace) {
- sev->replace(&kev->event, ev);
+ if (sev->ops && sev->ops->replace) {
+ sev->ops->replace(&kev->event, ev);
copy_payload = false;
}
- } else if (sev->merge) {
+ } else if (sev->ops && sev->ops->merge) {
struct v4l2_kevent *second_oldest =
sev->events + sev_pos(sev, 0);
- sev->merge(&kev->event, &second_oldest->event);
+ sev->ops->merge(&kev->event, &second_oldest->event);
}
}

@@ -208,8 +216,14 @@ static void ctrls_merge(const struct v4l2_event *old, struct v4l2_event *new)
new->u.ctrl.changes |= old->u.ctrl.changes;
}

+static const struct v4l2_subscribed_event_ops ctrl_ops = {
+ .replace = ctrls_replace,
+ .merge = ctrls_merge,
+};
+
int v4l2_event_subscribe(struct v4l2_fh *fh,
- struct v4l2_event_subscription *sub, unsigned elems)
+ struct v4l2_event_subscription *sub, unsigned elems,
+ const struct v4l2_subscribed_event_ops *ops)
{
struct v4l2_subscribed_event *sev, *found_ev;
struct v4l2_ctrl *ctrl = NULL;
@@ -236,10 +250,9 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
sev->id = sub->id;
sev->flags = sub->flags;
sev->fh = fh;
- sev->elems = elems;
+ sev->ops = ops;
if (ctrl) {
- sev->replace = ctrls_replace;
- sev->merge = ctrls_merge;
+ sev->ops = &ctrl_ops;
}

spin_lock_irqsave(&fh->vdev->fh_lock, flags);
@@ -248,12 +261,27 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
list_add(&sev->list, &fh->subscribed);
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);

- /* v4l2_ctrl_add_event uses a mutex, so do this outside the spin lock */
- if (found_ev)
+ if (found_ev) {
kfree(sev);
- else if (ctrl)
+ return 0; /* Already listening */
+ }
+
+ if (sev->ops && sev->ops->add) {
+ int ret = sev->ops->add(sev);
+ if (ret) {
+ sev->ops = NULL;
+ v4l2_event_unsubscribe(fh, sub);
+ return ret;
+ }
+ }
+
+ /* v4l2_ctrl_add_event uses a mutex, so do this outside the spin lock */
+ if (ctrl)
v4l2_ctrl_add_event(ctrl, sev);

+ /* Mark as ready for use */
+ sev->elems = elems;
+
return 0;
}
EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
@@ -306,6 +334,10 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
}

spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+
+ if (sev && sev->ops && sev->ops->del)
+ sev->ops->del(sev);
+
if (sev && sev->type == V4L2_EVENT_CTRL) {
struct v4l2_ctrl *ctrl = v4l2_ctrl_find(fh->ctrl_handler, sev->id);

diff --git a/drivers/usb/gadget/uvc_v4l2.c b/drivers/usb/gadget/uvc_v4l2.c
index f6e083b..90db5fe 100644
--- a/drivers/usb/gadget/uvc_v4l2.c
+++ b/drivers/usb/gadget/uvc_v4l2.c
@@ -296,7 +296,7 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
if (sub->type < UVC_EVENT_FIRST || sub->type > UVC_EVENT_LAST)
return -EINVAL;

- return v4l2_event_subscribe(&handle->vfh, arg, 2);
+ return v4l2_event_subscribe(&handle->vfh, arg, 2, NULL);
}

case VIDIOC_UNSUBSCRIBE_EVENT:
diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
index 5f14e88..88fa9a1 100644
--- a/include/media/v4l2-event.h
+++ b/include/media/v4l2-event.h
@@ -78,6 +78,19 @@ struct v4l2_kevent {
struct v4l2_event event;
};

+/** struct v4l2_subscribed_event_ops - Subscribed event operations.
+ * @add: Optional callback, called when a new listener is added
+ * @del: Optional callback, called when a listener stops listening
+ * @replace: Optional callback that can replace event 'old' with event 'new'.
+ * @merge: Optional callback that can merge event 'old' into event 'new'.
+ */
+struct v4l2_subscribed_event_ops {
+ int (*add)(struct v4l2_subscribed_event *sev);
+ void (*del)(struct v4l2_subscribed_event *sev);
+ void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
+ void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
+};
+
/** struct v4l2_subscribed_event - Internal struct representing a subscribed event.
* @list: List node for the v4l2_fh->subscribed list.
* @type: Event type.
@@ -85,8 +98,7 @@ struct v4l2_kevent {
* @flags: Copy of v4l2_event_subscription->flags.
* @fh: Filehandle that subscribed to this event.
* @node: List node that hooks into the object's event list (if there is one).
- * @replace: Optional callback that can replace event 'old' with event 'new'.
- * @merge: Optional callback that can merge event 'old' into event 'new'.
+ * @ops: v4l2_subscribed_event_ops
* @elems: The number of elements in the events array.
* @first: The index of the events containing the oldest available event.
* @in_use: The number of queued events.
@@ -99,10 +111,7 @@ struct v4l2_subscribed_event {
u32 flags;
struct v4l2_fh *fh;
struct list_head node;
- void (*replace)(struct v4l2_event *old,
- const struct v4l2_event *new);
- void (*merge)(const struct v4l2_event *old,
- struct v4l2_event *new);
+ const struct v4l2_subscribed_event_ops *ops;
unsigned elems;
unsigned first;
unsigned in_use;
@@ -115,7 +124,8 @@ void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
int v4l2_event_pending(struct v4l2_fh *fh);
int v4l2_event_subscribe(struct v4l2_fh *fh,
- struct v4l2_event_subscription *sub, unsigned elems);
+ struct v4l2_event_subscription *sub, unsigned elems,
+ const struct v4l2_subscribed_event_ops *ops);
int v4l2_event_unsubscribe(struct v4l2_fh *fh,
struct v4l2_event_subscription *sub);
void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
--
1.7.9.3