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Commit 98ec6339 authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
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V4L/DVB (11021): v4l2-device: add a notify callback. 



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

Signed-off-by: default avatarHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 00575961

Documentation/video4linux/v4l2-framework.txt

+10 −0
Original line number Diff line number Diff line
@@ -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

include/media/v4l2-device.h

+3 −0
Original line number Diff line number Diff line
@@ -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.

include/media/v4l2-subdev.h

+5 −0
Original line number Diff line number Diff line
@@ -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