Link training is the process of obtaining link synchronization between two ports attached via a 1x, 4x, or 12x link.
Link training is initiated when a port's receive logic receives a TS1 Ordered Set (referred to as the beacon sequence) from the port at the other end of the link. This happens when a port's Physical Layer receives a PowerOnReset, a LinkPhyReset (from the Link Layer), or when a hot plug event occurs.
The link training process includes:
Link width and speed negotiation.
The training sequence handshake.
Error recovery from transient link errors.
During the training process, the ports at each end of the link learn each other's capabilities and configure the following ...