Figure 14-5 on page 510 illustrates the top-level states of the Link Training and Status State Machine (LTSSM). Each state consists of substates that, taken together, comprise that state. The first LTSSM state entered after exiting Fundamental Reset (Cold or Warm Reset) or Hot Reset is the Detect state.
The LTSSM consists of 11 top-level states: Detect, Polling, Configuration, Recovery, L0, L0s, L1, L2, Hot Reset, Loopback, and Disable. These states can be grouped into five categories:
The Link Training states.
A Link Re-Training State. ...