I have done some tests on a PCIe gen 2 based USB3380 card on an IMX6Q-based reference board using the latest mainline kernel with associated net2280 driver.
The only way, at the moment to make it work is to force gen 1 link speed.
Is this common for all gen 2 cards?
Are there fixes or patches available that will make it possible to reenable gen 2?
I guess that this problem is related to Re: i.MX6Q: Re-establishing a PCIe link and errata ERR005184.