diff options
Diffstat (limited to 'Documentation/video4linux')
| -rw-r--r-- | Documentation/video4linux/v4l2-framework.txt | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt index eb8479565dc..7de55cfae04 100644 --- a/Documentation/video4linux/v4l2-framework.txt +++ b/Documentation/video4linux/v4l2-framework.txt @@ -83,11 +83,17 @@ You must register the device instance: v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev); -Registration will initialize the v4l2_device struct and link dev->driver_data -to v4l2_dev. If v4l2_dev->name is empty then it will be set to a value derived -from dev (driver name followed by the bus_id, to be precise). If you set it -up before calling v4l2_device_register then it will be untouched. If dev is -NULL, then you *must* setup v4l2_dev->name before calling v4l2_device_register. +Registration will initialize the v4l2_device struct. If the dev->driver_data +field is NULL, it will be linked to v4l2_dev. Drivers that use the media +device framework in addition to the V4L2 framework need to set +dev->driver_data manually to point to the driver-specific device structure +that embed the struct v4l2_device instance. This is achieved by a +dev_set_drvdata() call before registering the V4L2 device instance. + +If v4l2_dev->name is empty then it will be set to a value derived from dev +(driver name followed by the bus_id, to be precise). If you set it up before +calling v4l2_device_register then it will be untouched. If dev is NULL, then +you *must* setup v4l2_dev->name before calling v4l2_device_register. You can use v4l2_device_set_name() to set the name based on a driver name and a driver-global atomic_t instance. This will generate names like ivtv0, ivtv1, @@ -108,6 +114,7 @@ You unregister with: v4l2_device_unregister(struct v4l2_device *v4l2_dev); +If the dev->driver_data field points to v4l2_dev, it will be reset to NULL. 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 |