diff options
author | Hans Verkuil <hverkuil@xs4all.nl> | 2011-02-24 06:28:46 -0300 |
---|---|---|
committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2011-03-22 16:38:06 -0300 |
commit | 2335e2b817186cf79a07311f14560ef8b30f6a9a (patch) | |
tree | c75b6d5f12c41734c01310409f7f26cfe65ee3dc /Documentation/video4linux | |
parent | bedf8bcf6b4f90a6e31add3721a2e71877289381 (diff) | |
download | linux-3.10-2335e2b817186cf79a07311f14560ef8b30f6a9a.tar.gz linux-3.10-2335e2b817186cf79a07311f14560ef8b30f6a9a.tar.bz2 linux-3.10-2335e2b817186cf79a07311f14560ef8b30f6a9a.zip |
[media] v4l2-framework.txt: document new v4l2_device release() callback
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/video4linux')
-rw-r--r-- | Documentation/video4linux/v4l2-framework.txt | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt index 1c8d4492f5c..7d09114af00 100644 --- a/Documentation/video4linux/v4l2-framework.txt +++ b/Documentation/video4linux/v4l2-framework.txt @@ -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 ------------------ |