For a detailed description of the diagnostic signals which are available to debug the RX, see Port Descriptions.
If the Ethernet packets are being transmitted properly according to IEEE Std 802.3-2015, there should not be RX errors. However, the signal integrity of the received signals must be verified first.
The stat_rx_bip_err signals provide a per-lane indicator of signal
quality. The stat_rx_hi_ber signal is asserted when the bit error rate is
too high, according to IEEE Std 802.3-2015. The threshold is BER = 10–4.
To aid in debug, GT near-end PMA loopback can be performed with the
gt_loopback_in signal. This connects the TX SerDes to the RX SerDes,
effectively bypassing potential signal integrity problems. In this way, the received data
can be checked against the transmitted packets to verify that the logic is operating
properly.