Several drivers need to do something when the first filehandle is opened
or the last filehandle is closed. Most implement some use count mechanism,
but if they use v4l2_fh, then you can also just check if this is the only
filehandle for the device node. A simple helper function can do this.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Add two new functions: v4l2_fh_open allocates and initializes a struct v4l2_fh
based on a struct file pointer and v4l2_fh_release releases and frees a struct
v4l2_fh.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Add event handling backend to V4L2. The backend handles event subscription
and delivery to file handles. Event subscriptions are based on file handle.
Events may be delivered to all subscribed file handles on a device
independent of where they originate from.
Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This patch adds a list of v4l2_fh structures to every video_device.
It allows using file handle related information in V4L2. The event interface
is one example of such use.
The use of v4l2_fh is not mandatory for drivers.
Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
