To enable auto negotiation:
1. Set ctl_autoneg_enable to 1.
2. Set ctl_autoneg_bypass to 0.
3. Set ctl_an_* to advertise the desired AN settings.
When using control and status interface, the example design ties off the ctl_an_* values to valid settings. If you are using register interface, see the Auto-Negotiation and Link Training for register sequence.
To enable link training, set ctl_lt_training_enable to 0.
Note: The core does not actually do any training. It only provides the control protocol required by section 72.6.10. The training algorithm is a user responsibility.
The core does not monitor the RX eye nor does it send any presets, initializations, or coefficient control requests to the link partner TX. It is recommended to set ctl_lt_rx_trained to 1. Setting ctl_lt_rx_trained tells the link partner that your RX training is completed, and that you will not be sending any more presets, initializations, or coefficient changes.
The core does not adjust any of the GT TX amplitude or coefficient control settings in response to any training messages received from the link partner. The example design link training Place_Holder Logic will indicate that maximum limits have been reached. This should allow link training to complete.