Expand description
CDC-specific request codes.
This carried a note saying usb-serial “does not implement CDC class control
requests yet”, which stopped being true some time ago and is worth correcting
rather than leaving: UsbCdcAcmSerialHandler::handle_control
(src/server/usb/serial/handler.rs) matches on these constants and answers
SET_LINE_CODING, GET_LINE_CODING, SET_CONTROL_LINE_STATE and SEND_BREAK
itself. SEND_ENCAPSULATED_COMMAND and GET_ENCAPSULATED_RESPONSE fall
through to the catch-all, which answers empty on purpose — an error would
abort the USB/IP session for the whole device, and a host probing an optional
request must not unplug the port.