Agilex™ 5 ES Device Errata and User Guidelines

ID 825514
Date 12/09/2024
Public
Document Table of Contents

3.4.3. 2123467: No response to Debug APB access during a core reset, in Direct connect configuration

Description

If there is traffic to a core on the Debug APB bus when the core is powered off, the access should receive a PSLVERR response. If the core reset is applied, then the APB bus will not provide a response, which can lead to a system deadlock.

Conditions

  1. The core is in the OFF power mode.
  2. The system is asserting the nCPUPORESET core reset signal LOW.
  3. The DebugBlock remains powered ON.
  4. An access is made to the core on the Debug APB bus.

Impact

The PREADYDC and PSLVERRDC signals on the cluster APB interface are incorrectly driven LOW during reset, which means that any access in the interface will not receive a response. This can lead to a system deadlock.

Workaround

If the system and software can ensure that no APB accesses can be made while the core is powered off, then this will avoid this erratum.

If the system can assert the nPRESET signal to the DebugBlock whenever the core is powered off, then this will also avoid this erratum.

Category

Category C