7.1.1. 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.
- Link fails to negotiate to expected link speed.
- Link fails to negotiate to the expected link width.
- LTSSM fails to reach/stay stable at L0.
Flow Chart for Debugging Link Training Issues
Use the flow chart below to identify the potential cause of the issue seen during link training when using the P-Tile Avalon® -ST IP for PCI Express.
Note: (*) Redo the equalization using the Link Equalization Request 8.0 GT/s bit of the Link Status 2 register for 8.0 GT/s or Link Equalization Request 16.0 GT/s bit of the 16.0 GT/s Status Register.
Use the following debug tools for debugging link training issues observed on the PCI Express link when using the P-tile Avalon® -ST IP for PCI Express.