For one disclosed embodiment, a controller comprises communication circuitry to communicate over one or more data lines with a downstream device external to an upstream device having the controller and detection circuitry to detect on at least one of the one or more data lines a voltage having a value in excess of a reference value. The detection circuitry is to deactivate a supply of power over one or more power lines to the downstream device in response to detection on at least one of the one or more data lines of a voltage having a value in excess of the reference value. Other embodiments are also disclosed.