There are two different timers for the overcurrent condition, one for an enabled port and the other for a disabled port. Both these timers are used for making sure when an overcurrent condition occurs, the hub will report it after the time set in bits 0..3 (for disabled port) and bits 4..7 (for enabled port) of byte 7 of the EEPROM. The difference is that an enabled port might lose its configuration information if there is a power glitch, while a disabled port has no such problem. A disabled port will need a bus reset to make it enabled, and this reset should restore its operation. In essence, this is an extra filter for overcurrent conditions.