PORT_PWR_STANDBY
if (serial_refcount == 1 && serial_power == PORT_PWR_STANDBY)
if (!serial_refcount && serial_power == PORT_PWR_STANDBY)
(serial_power == PORT_PWR_STANDBY && !serial_refcount))
case PORT_PWR_STANDBY:
serial_power = PORT_PWR_STANDBY;
(serial_power == PORT_PWR_STANDBY && serial_refcount))
serial_power = PORT_PWR_STANDBY;