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TCM arbitration hazard: Considerations for Firmware

c0deface over 4 years ago

According to the ARM spec (ARM DDI 0460D section 8.4.4):

TCM arbitration

Each TCM port receives requests from the LSU, PFU, and AXI slave. In most cases, the LSU

has the highest priority, followed by the PFU, with the AXI slave having lowest priority.

When a higher-priority device is accessing a TCM port, an access from a lower-priority device

must stall. When either the LSU or the AXI slave interface is performing a read-modify-write

operation on a TCM port, various internal data hazards exist for either the AXI-slave interface

or the LSU. In these cases, additional stall cycles are generated, beyond those normally

required for arbitration.

Is there something special that the firmware should do for such hazard ?