1. An, apparatus, comprising: an interface unit configured to receive data via a serial interface. circuitry configured to: determine a number of errors in the data; perform one or more first training operations on the serial interface responsive to a determination that the number of errors in the data is greater than or equal to a first threshold value; and perform a second training operation on the serial interface responsive to a determination that a number of first training operations performed during a predetermined period of time is greater than or equal to a second threshold value, wherein a time to perform the second training operation is greater than a time to perform each of the one or more first training operations.