Type Alias IOUSBHostControllerInterfaceDoorbellHandler 

pub type IOUSBHostControllerInterfaceDoorbellHandler = *mut DynBlock<dyn Fn(NonNull<IOUSBHostControllerInterface>, NonNull<IOUSBHostCIDoorbell>, u32)>;

Available on crate features IOUSBHostControllerInterface and IOUSBHostControllerInterfaceDefinitions and block2 only.

Client-supplied block to handle IOUSBHostCIDoorbell messages

The kernel driver sends IOUSBHostCIDoorbell messages to notify the client that transfer structures for specific endpoints have been updated. Doorbell messages should be processed by a client-created IOUSBHostCIEndpointStateMachine.

See also Apple’s documentation