Why does the Stratix® 10 Avalon® -MM Interface for PCIe* IP with internal DMA send out the read mover "Done" status before it completes the data transfer?

Description

This problem is due to a datapath race condition. The DMA read mover "Done" status update and the completion data are split internally into two (2) different paths/buffers. Data takes a longer path to the Avalon® -MM slave compared to the status update.

Resolution

This datapath race condition is easily observed in simulation. However, the read mover "Done" status reported a few clock cycles earlier than the data transfer completion will not be a problem in real hardware systems due to latency.