RETURN_ERROR(SP_ERR_ARG, "Null port");
if (port->transport != SP_TRANSPORT_USB)
RETURN_ERROR(SP_ERR_ARG, "Port does not use USB transport");
RETURN_ERROR(SP_ERR_ARG, "Null port");
if (port->transport != SP_TRANSPORT_USB)
RETURN_ERROR(SP_ERR_ARG, "Port does not use USB transport");