Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 4/01/2024
Public
Document Table of Contents

4.1.5.15.1. Q-Channel

To support the flush and drain of the F2H interface from the fabric, the CCU has been divided into two power domains. Most of the CCU is in an always-on power domain, while NCAIU0 for the F2H interface is in a separate clock-only power domain.

The ability to disable power to NCAIU0 is not supported. Instead, the addition of the F2H power domain adds a Q-channel that is utilized by the reset manager to flush and drain any outstanding traffic from the F2H bridge that remains after the flush and drain of the bridge itself is completed. This ensures that all traffic from the fabric is cleared before reset is asserted.

The following figure shows a Q-channel handshake.

Figure 30. Q-Channel Handshake

When the reset manager asserts the QREQn input to NCAIU0 at T2, the CCU begins a fence and drain of all outstanding traffic on the F2H. When all traffic completes, the CCU asserts QACCEPTn back to the reset manager.