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V4L/DVB (11021): v4l2-device: add a notify callback.

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Add a notify callback to v4l2_device to let sub-devices notify their
parent of special events.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans Verkuil 2009-03-08 17:02:10 -03:00 committed by Mauro Carvalho Chehab
parent 005759613b
commit 98ec633972
3 changed files with 18 additions and 0 deletions
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10
Documentation/video4linux/v4l2-framework.txt
View File

@ -94,6 +94,11 @@ usb_device or platform_device. It is rare for dev to be NULL, but it happens
with ISA devices or when one device creates multiple PCI devices, thus making
it impossible to associate v4l2_dev with a particular parent.
You can also supply a notify() callback that can be called by sub-devices to
notify you of events. Whether you need to set this depends on the sub-device.
Any notifications a sub-device supports must be defined in a header in
include/media/<subdevice>.h.
You unregister with:
v4l2_device_unregister(struct v4l2_device *v4l2_dev);
@ -281,6 +286,11 @@ e.g. AUDIO_CONTROLLER and specify that as the group ID value when calling
v4l2_device_call_all(). That ensures that it will only go to the subdev
that needs it.
If the sub-device needs to notify its v4l2_device parent of an event, then
it can call v4l2_subdev_notify(sd, notification, arg). This macro checks
whether there is a notify() callback defined and returns -ENODEV if not.
Otherwise the result of the notify() call is returned.
The advantage of using v4l2_subdev is that it is a generic struct and does
not contain any knowledge about the underlying hardware. So a driver might
contain several subdevs that use an I2C bus, but also a subdev that is

3
include/media/v4l2-device.h
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@ -44,6 +44,9 @@ struct v4l2_device {
spinlock_t lock;
/* unique device name, by default the driver name + bus ID */
char name[V4L2_DEVICE_NAME_SIZE];
/* notify callback called by some sub-devices. */
void (*notify)(struct v4l2_subdev *sd,
unsigned int notification, void *arg);
};
/* Initialize v4l2_dev and make dev->driver_data point to v4l2_dev.

5
include/media/v4l2-subdev.h
View File

@ -191,4 +191,9 @@ static inline void v4l2_subdev_init(struct v4l2_subdev *sd,
(!(sd) ? -ENODEV : (((sd) && (sd)->ops->o && (sd)->ops->o->f) ? \
(sd)->ops->o->f((sd) , ##args) : -ENOIOCTLCMD))
/* Send a notification to v4l2_device. */
#define v4l2_subdev_notify(sd, notification, arg) \
((!(sd) || !(sd)->v4l2_dev || !(sd)->v4l2_dev->notify) ? -ENODEV : \
(sd)->v4l2_dev->notify((sd), (notification), (arg)))
#endif