Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-12-01 00:21:32 +00:00
Code Issues Packages Projects Releases Wiki Activity

[media] v4l2-framework.txt: document new v4l2_device release() callback

Browse Source 
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans Verkuil 2011-02-24 06:28:46 -03:00 committed by Mauro Carvalho Chehab
parent bedf8bcf6b
commit 2335e2b817
1 changed files with 15 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
Documentation/video4linux/v4l2-framework.txt
View File

@ -181,6 +181,21 @@ static int __devinit drv_probe(struct pci_dev *pdev,
state->instance = atomic_inc_return(&drv_instance) - 1;
}
If you have multiple device nodes then it can be difficult to know when it is
safe to unregister v4l2_device. For this purpose v4l2_device has refcounting
support. The refcount is increased whenever video_register_device is called and
it is decreased whenever that device node is released. When the refcount reaches
zero, then the v4l2_device release() callback is called. You can do your final
cleanup there.
If other device nodes (e.g. ALSA) are created, then you can increase and
decrease the refcount manually as well by calling:
void v4l2_device_get(struct v4l2_device *v4l2_dev);
or:
int v4l2_device_put(struct v4l2_device *v4l2_dev);
struct v4l2_subdev
------------------