GTX, GTY far-end PCS

[poo053]

I have a board that uses gtx and a board that uses gty.
Both boards use comma detection and clock correction.
We confirmed that they operate normally under normal conditions.
However, setting the gtx board to normal, the gty board to far-end pcs, and testing the far-end pcs of the gtx board will not work properly. The same goes for the gty board.
The remaining loopback operations operate normally.
I was wondering if you want to test the far-end pcs of the gtx board, gty should turn off clock correction.
Please help me.

[gguasti]

hello

this might be a problem of the clock tree:

from the UG578:

Far-end PCS Loopback (path 4 in Figure 2-28)
If clock correction is not used, a transceiver in far-end PCS loopback must use the same
reference clock used by the transceiver that is the source of the loopback data.

Regardless of whether or not clock correction is used, the TXUSRCLK and RXUSRCLK
ports must be driven by the same clocking resource (BUFG_GT). Far-end PCS loopback is
not supported when both or either gearboxes in the channel are enabled.