TX2: PCIe Polarity Inversion: Supported? Working?

Robotics & Edge Computing Jetson & Embedded Systems Jetson TX2
1

I’m having PCIe problems on a custom TX2 board. PCIe endpoints won’t show up.

Question: I’m using PCIe Polarity inversion according to section 4.2.4.4 of the PCIe Base Specification 2.1 on all lanes of the x4 PCIe due to layout issues. RefClk is not inverted.

Is this configuration supported on TX2?
Has this been verified in real hardware?

2

What do you mean by “on all lanes of the x4 PCIe” exactly?
If that means, you are inverting polarity on Tx lanes, then, the endpoint you are connecting should also support lane polarity inversion, otherwise, it won’t work.
Since lane polarity inversion is a receiver specific feature, and since Tegra’s root port does support this, it can work with lane polarity inversion. But, point to note here is that, just because, it has detected polarity inversion on its Rx lanes, it doesn’t send data inverted on its Tx lanes. So, if you are inverting Tx lanes, then, make sure that your endpoint supports lane polarity inversion.