How does the rx_st_mask signal affect the behavior of the Hard IP for PCI Express in Arria 10?

Description

The Avalon®-ST variant of the Altera® Arria® 10 Hard IP for PCI® Express includes the signal rx_st_mask.  As stated in the user guide description, you can use this signal to stop sending non-posted requests.

Resolution

This signal stalls non-posted TLPs. All other TLP types continue to be forwarded to the Application Layer.

The stalled non-posted TLPs are held in the RX buffer until the mask signal is deasserted.  They are not discarded.

When used in a Root Port mode, the rx_st_mask signal stalls all IO read, memory read, and configuration accesses (non-posted transactions).