diff options
Diffstat (limited to 'Documentation/video4linux/v4l2-framework.txt')
| -rw-r--r-- | Documentation/video4linux/v4l2-framework.txt | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt index 24353ecab197..b5e6347b720f 100644 --- a/Documentation/video4linux/v4l2-framework.txt +++ b/Documentation/video4linux/v4l2-framework.txt @@ -574,9 +574,13 @@ of the video device exits. The default video_device_release() callback just calls kfree to free the allocated memory. +There is also a video_device_release_empty() function that does nothing +(is empty) and can be used if the struct is embedded and there is nothing +to do when it is released. + You should also set these fields: -- v4l2_dev: set to the v4l2_device parent device. +- v4l2_dev: must be set to the v4l2_device parent device. - name: set to something descriptive and unique. @@ -613,15 +617,16 @@ You should also set these fields: If you want to have a separate priority state per (group of) device node(s), then you can point it to your own struct v4l2_prio_state. -- parent: you only set this if v4l2_device was registered with NULL as +- dev_parent: you only set this if v4l2_device was registered with NULL as the parent device struct. This only happens in cases where one hardware device has multiple PCI devices that all share the same v4l2_device core. The cx88 driver is an example of this: one core v4l2_device struct, but - it is used by both an raw video PCI device (cx8800) and a MPEG PCI device - (cx8802). Since the v4l2_device cannot be associated with a particular - PCI device it is setup without a parent device. But when the struct - video_device is setup you do know which parent PCI device to use. + it is used by both a raw video PCI device (cx8800) and a MPEG PCI device + (cx8802). Since the v4l2_device cannot be associated with two PCI devices + at the same time it is setup without a parent device. But when the struct + video_device is initialized you *do* know which parent PCI device to use and + so you set dev_device to the correct PCI device. - flags: optional. Set to V4L2_FL_USE_FH_PRIO if you want to let the framework handle the VIDIOC_G/S_PRIORITY ioctls. This requires that you use struct |