Xavier-8gb, pcie 4lane loopback

I’m testing the function of pcie of the xavier-8gb. At first, I want to confirm whether the loopback of pcie is OK or not. Please tell me how to test the loopback of pcie 4lane.

Moving to Jetson AGX Xavier forum.

As far as the loopback mode of PCIe is confirmed, it works fine, but please make sure that the max speed of the controller is set to either Gen-1 or Gen-2. Although all controllers support up to Gen-4 speed when they are tested in the loopback configuration, the equalization won’t happen, so the link can’t go to Gen-3/4 speeds.
For testing loopback configuration, Tx and Rx lines can be shorted.

”For testing loopback configuration, Tx and Rx lines can be shorted.“
Do you mean I need not set related register besides shorting the Tx and Rx lines.I read the datasheet and many register is related to loopback.
Can you write the all sequence to realize loopback?

What kind of loopback are you interested in? Since it is the loopback test, I assume, you may want to test your carrier board configuration, in which case, external loopback (i.e. Tx to Rx) is what you would want to test??

I mean if only short Tx to Rx,will the state training be running correctly?

Yes. As I mentioned before, set the max-speed to 1 or 2 and short Tx and Rx and you should be able to see the PCIe link going up.