A system includes a first device including a first transmitter and a first receiver, and a second device including a second transmitter and a second receiver and configured to communicate with the first device. The two devices perform a first equalization operation by performing a first phase in which the first receiver performs a signal tuning operation on the second transmitter, a second phase in which the second receiver performs a signal tuning operation on the first transmitter, and one or more other phases. The first, second, and other phases may constitute all the phases of the first equalization operation, and some of the other phases may precede the first and second phases. In response to detection of an error after the first equalization operation, the two devices may perform a second equalization operation by performing the first phase, the second phase, or both, but not performing the other phases.