How to test the PCIe connection?

After connecting my design board with Xavier, how can I make PCI respond to my design board hardware successfully?
I found the official driver sample file (/ Drivers / PCI / host), but the dmesg information indicated that I did not successfully connect to PCI
(PCIe link is not up…!)

You can check it by plug the devices which uses PCIe. We prefer to use M.2 SSD hardware.