Arria 10 Native PHY 66:64 RX wrong word with valid asserted

Hi,

Thanks for your update. I took a closer look at the user guide for the case where the PCS/PMA width is configured as 66/64.

In the RX direction, the soft gearbox repacks the 66-bit PCS blocks into 64-bit words toward the fabric. Because the two widths are unequal, the rates do not line up evenly: for every 32 input blocks (32 × 66 = 2112 bits), the gearbox produces 33 output words (33 × 64 = 2112 bits). As a result, one out of every 33 output cycles carries no valid data — which in your case, you would need the fabric logic needs to accommodate.

If you would prefer a continuous, non-backpressured stream, my understanding is that you can configure a matched (even) PCS/PMA width ratio so that no gap cycle is required.

Please let me know if you have any further questions. Thank you.