On our LS1046A board, we use a 5G copper PHY connect with XFI, the PHY is support 5G/2.5G BASE-T over XFI. But it expects to receive packets with sufficient Inter Packet Idles from the MAC (switch/controller) for the 5G or 2.5G rate effectively transfer over the XFI interface in 10GBASE-R mode.
Now we have a issue, when LS1046A transmit files to PC using FTP, the speed will up to 200MB/s，but the transition will blocked down after few seconds. And we need turn down and up the net on board to recover the net.
But when we change MTU from 1500 to 800, or use tc tools, the net will not down, but the speed will degrade fast from 200MB/s to 100MB/s, specially transmit 2 or more file at same time.
So we think it may be MAC transmit packets too fast to make PHY receiver buffer overflow.
Can XFI insert Inter Packet Idles according to cooper speed? We try to modify Transmit Inter-Packet Gap Length Register, But the problem still there.