Signed-off-by: Hans Verkuil <hverkuil@xxxxxxxxx> --- Documentation/video4linux/v4l2-framework.txt | 19 +++++++++++++++++-- 1 files changed, 17 insertions(+), 2 deletions(-) diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt index f22f35c..7739705 100644 --- a/Documentation/video4linux/v4l2-framework.txt +++ b/Documentation/video4linux/v4l2-framework.txt @@ -448,15 +448,20 @@ allocated memory. You should also set these fields: - v4l2_dev: set to the v4l2_device parent device. + - name: set to something descriptive and unique. + - fops: set to the v4l2_file_operations struct. + - ioctl_ops: if you use the v4l2_ioctl_ops to simplify ioctl maintenance (highly recommended to use this and it might become compulsory in the future!), then set this to your v4l2_ioctl_ops struct. + - lock: leave to NULL if you want to do all the locking in the driver. Otherwise you give it a pointer to a struct mutex_lock and before any of the v4l2_file_operations is called this lock will be taken by the core and released afterwards. + - 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. @@ -467,8 +472,18 @@ You should also set these fields: 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. -If you use v4l2_ioctl_ops, then you should set either .unlocked_ioctl or -.ioctl to video_ioctl2 in your v4l2_file_operations struct. +- prio: if left to NULL, then the prio state in struct v4l2_device will be + used, otherwise you can point it to your own struct v4l2_prio_state. + This field is used for checking priorities (see VIDIOC_S_PRIORITY). In most + cases this field remains NULL. + + Only if the driver has multiple device nodes and some of those can be used + independently from others (e.g. capture and display nodes are often + independent), then you need to have multiple v4l2_prio_state structs and + point this field to the correct one. + +If you use v4l2_ioctl_ops, then you should set .unlocked_ioctl to video_ioctl2 +in your v4l2_file_operations struct. The v4l2_file_operations struct is a subset of file_operations. The main difference is that the inode argument is omitted since it is never used. -- 1.6.4.2 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
