RapidIO Intel FPGA IP User Guide

ID 683884
Date 9/15/2021
Public
Document Table of Contents

3.3.3. I/O Read and Write Order Preservation

I/O read and write order preservation controls support for order preservation between read and write operations (NWRITE, NWRITE_R, SWRITE, and NREAD requests) in the I/O Avalon® -MM Logical layer slave module. By default this feature is turned off.

This parameter is available only if you set I/O logical layer Interfaces to Avalon® -MM Master and Slave or Avalon® -MM Slave.

This parameter is not available for variations that target Intel® Arria® 10 and Intel® Cyclone® 10 GX devices. RapidIO IP core Intel® Arria® 10 and Intel® Cyclone® 10 GX variations that include an I/O Logical layer Avalon® -MM slave module preserve transaction ordering between read and write operations in the I/O Avalon® -MM Logical layer slave module.

Whether you turn on this feature or not, as required by the Avalon® -MM specification, each individual Logical layer Avalon® -MM slave module preserves response order. Even if the responses to two requests from the same Logical layer Avalon® -MM slave module arrive in reverse order on the RapidIO link, the Logical layer module enforces the response order on the Avalon® -MM interface. The slave module enforces the order by maintaining a queue of the Transaction IDs of transactions awaiting responses from the RapidIO link.