SNLS638A December 2018 – August 2019 DP83825I
Far-End (Reverse) loopback is a special test mode to allow PHY testing with a link partner. In this mode, data that is received from the Link Partner passes through the PHY’s receiver, is looped back at the MAC interface and then transmitted back to the Link Partner. While in Reverse Loopback mode, all data signals that come from the MAC are ignored. It requires 100-Ω terminations across pins #1 and #2.
Reverse Loopback is enabled by setting bit in the BISCR.