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V4L/DVB (11044): v4l2-device: add v4l2_device_disconnect

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Call v4l2_device_disconnect when the parent of a hotpluggable device
disconnects. This ensures that you do not have a pointer to a device that
is no longer present.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans Verkuil 2009-03-14 08:28:45 -03:00 committed by Mauro Carvalho Chehab
parent 6273fda6e3
commit ae6cfaace1
4 changed files with 27 additions and 6 deletions
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1
Documentation/video4linux/CARDLIST.bttv
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@ -157,4 +157,3 @@
156 -> IVCE-8784 [0000:f050,0001:f050,0002:f050,0003:f050]
157 -> Geovision GV-800(S) (master) [800a:763d]
158 -> Geovision GV-800(S) (slave) [800b:763d,800c:763d,800d:763d]
159 -> ProVideo PV183 [1830:1540,1831:1540,1832:1540,1833:1540,1834:1540,1835:1540,1836:1540,1837:1540]

11
Documentation/video4linux/v4l2-framework.txt
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@ -105,6 +105,17 @@ You unregister with:
Unregistering will also automatically unregister all subdevs from the device.
If you have a hotpluggable device (e.g. a USB device), then when a disconnect
happens the parent device becomes invalid. Since v4l2_device has a pointer to
that parent device it has to be cleared as well to mark that the parent is
gone. To do this call:
v4l2_device_disconnect(struct v4l2_device *v4l2_dev);
This does *not* unregister the subdevs, so you still need to call the
v4l2_device_unregister() function for that. If your driver is not hotpluggable,
then there is no need to call v4l2_device_disconnect().
Sometimes you need to iterate over all devices registered by a specific
driver. This is usually the case if multiple device drivers use the same
hardware. E.g. the ivtvfb driver is a framebuffer driver that uses the ivtv

15
drivers/media/video/v4l2-device.c
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@ -49,19 +49,26 @@ int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
}
EXPORT_SYMBOL_GPL(v4l2_device_register);
void v4l2_device_disconnect(struct v4l2_device *v4l2_dev)
{
if (v4l2_dev->dev) {
dev_set_drvdata(v4l2_dev->dev, NULL);
v4l2_dev->dev = NULL;
}
}
EXPORT_SYMBOL_GPL(v4l2_device_disconnect);
void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
{
struct v4l2_subdev *sd, *next;
if (v4l2_dev == NULL)
return;
if (v4l2_dev->dev)
dev_set_drvdata(v4l2_dev->dev, NULL);
v4l2_device_disconnect(v4l2_dev);
/* Unregister subdevs */
list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list)
v4l2_device_unregister_subdev(sd);
v4l2_dev->dev = NULL;
}
EXPORT_SYMBOL_GPL(v4l2_device_unregister);

6
include/media/v4l2-device.h
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@ -53,7 +53,11 @@ struct v4l2_device {
dev may be NULL in rare cases (ISA devices). In that case you
must fill in the v4l2_dev->name field before calling this function. */
int __must_check v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev);
/* Set v4l2_dev->dev->driver_data to NULL and unregister all sub-devices */
/* Set v4l2_dev->dev to NULL. Call when the USB parent disconnects.
Since the parent disappears this ensures that v4l2_dev doesn't have an
invalid parent pointer. */
void v4l2_device_disconnect(struct v4l2_device *v4l2_dev);
/* Unregister all sub-devices and any other resources related to v4l2_dev. */
void v4l2_device_unregister(struct v4l2_device *v4l2_dev);
/* Register a subdev with a v4l2 device. While registered the subdev module