9.13.4. Phase 3 (Optional)
During this phase, the Root Port tunes the Endpoint’s transmitter. This process is analogous to Phase 2 but operates in the opposite direction.
Once Phase 3 tuning is complete, the Root Port moves to Recovery.RcvrLock, sending EC=2’b00, along with the final coefficients or preset agreed upon in Phase 2. The Endpoint moves to Recovery.RcvrLock using the final coefficients or preset agreed upon in Phase 3.