Hi Vidyas,
Thanks for the quick reply.
I checked the circuits these days, it looks the same routing with the EV kit board P2597. Anyway, i will try to get a PCIe loopback card and double check it. Do you have a recommendation for the PCIe loopback card? I tried to search it on online but failed to find a M.2(M-key) PCIe loopback card.
Meanwhile, is it possible that the problem came from the software setting? I found your solution to a similar problem in the post “PCIe-USB bridge can't be detected by TX2 - #13 by JasonFan”, it said “delay applying reset to end point by 100ms after refclk started”, where (in which file) to make this change?