What are the lnk_fwdclk_p/n clock signals that appear when targeting UltraScale devices, and how are they to be used?
The lnk_fwdclk_p and lnk_fwdclk_n clock signals are for the DisplayPort core when targeting UltraScale devices.
They are used with the DP159 retimer and provide a forwarded reference clock input from the DP159.
When targeting UltraScale, the DisplayPort Sink requires 2 reference clocks.
Note: The use of the DP159 is required for the DisplayPort Sink.
This is because the DisplayPort Sink and driver are designed to use the reference clock that is forwarded through the DP159 retimer.