__v4l2_async_register_subdev
EXPORT_SYMBOL(__v4l2_async_register_subdev);
ret = __v4l2_async_register_subdev(sd, module);
__v4l2_async_register_subdev(sd, THIS_MODULE)
int __v4l2_async_register_subdev(struct v4l2_subdev *sd, struct module *module);