Why is the o_rx_pfc port enabled for longer durations than normal when generating designs at 400G SIP using the F-Tile Ethernet Hard IP with Priority Flow Control (PFC) enabled?

Description

Due to a problem in the Quartus® Prime Pro Edition software version 25.3, you may see longer durations of “o_rx_pfc” port enabled in the example designs generated using the F-Tile Ethernet Hard IP at data rates of 400G SIP with PFC enabled.
When PFC is enabled, if packets received are more than the maximum configured frame size of the receiver, along with which if packet truncation is also enabled on the receiver side, then the packets are truncated, causing data_valid to deassert. This deasserted data_valid signal is affecting the counters of o_rx_pfc to stretch the pause signal duration.

Resolution

This problem is scheduled to be fixed in a future release of the Quartus® Prime Pro Edition software.