R-Tile Avalon® Streaming Intel® FPGA IP for PCI Express* User Guide

ID 683501
Date 4/10/2024
Document Table of Contents

6.1.1. Debugging Link Training Issues

The Physical Layer automatically performs link training and initialization without software intervention. This is a well-defined process to configure and initialize the device's Physical Layer and link so that PCIe packets can be transmitted.

Some examples of link training issues may include:
  • Link fails to negotiate to the expected link speed.
  • Link fails to negotiate to the expected link width.
  • LTSSM fails to reach/stay stable at L0.

Use the flow chart below to identify the potential cause of a link training problem when using the R-Tile Avalon-ST IP for PCI Express.

Figure 59. Link Training Debug Flow
Note: To reinitiate the equalization procedure, write 1b to the Perform Equalization bit [0] in the Link Control 3 register.