Agilex™ 7 F-Series and I-Series Known Issue List

ID 683584
Date 3/13/2025
Public
Document Table of Contents

2.1.1.8. F-Tile: Unsuccessful TX Equalization

Description

In the F-Tile Intel® FPGA IP for PCIe* , when a speed change to Gen3/Gen4 speed is attempted for the first time with full TxEq enabled, if all phases of equalization do not successfully complete, the link reverts back to the lowest speed that passed equalization. The Equalization results for Gen3 and Gen4 are recorded in the following registers:
  • For Gen3: Link Status 2 Register [4:1]:
    • [1] Equalization 8.0 GT/s Complete
    • [2] Equalization 8.0 GT/s Phase 1 Successful
    • [3] Equalization 8.0 GT/s Phase 2 Successful
    • [4] Equalization 8.0 GT/s Phase 3 Successful
  • For Gen4: 16.0 GT/s Status Register [3:0]​
    • [0] Equalization 16.0 GT/s Complete
    • [1] Equalization 16.0 GT/s Phase 1 Successful
    • [2] Equalization 16.0 GT/s Phase 2 Successful
    • [3] Equalization 16.0 GT/s Phase 3 Successful

If equalization is attempted, the “Complete” bit is set for that speed regardless if the other phases of equalization completed successfully. Once the “Complete” bit is set, the F-Tile permits a speed change by setting the Target Link Speed in the Link Control 2 Register. As a result, the link may train to Gen3/Gen4 speeds with sub-optimal transmitter equalization settings.​

To confirm if the transmitter equalization procedure completed successfully, use software to read the following registers and ensure that all bits are set:
  • For Gen3: Link Status 2 Register [4:1]
  • For Gen4: 16.0 GT/s Status Register [3:0]

To re-initiate the equalization procedure, write 1b to the Perform Equalization bit [0] in the Link Control 3 register.

Workaround

Use software to check that the link equalization procedure was successfully performed:
  • For Gen3: Both Equalization 8.0 GT/s Phase 3 Successful bit and Equalization 8.0 GT/s Complete bit of the Link Status 2 register are set to 1b.
  • For Gen4: Both Equalization 16.0 GT/s Phase 3 Successful bit and Equalization 16.0 GT/s Complete bit of 16.0 GT/s Status Register are set to 1b.
If required, re-initiate the link equalization procedure by:
  1. Writing 1b to the Perform Equalization bit in the Link Control 3 register.
  2. Followed by a write to the Target Link Speed field in the Link Control 2 register to enable the Link to run at 8.0 GT/s or higher.
  3. Followed by a write of 1b to the Retrain Link bit in the Link Control register of the Downstream Port.

Status

Table 10.  Device Status Table
Devices Affected Planned Fix
  • AGFxxxxxxxxxxxx
  • AGIxxxxxxxxxxxx
None