USB expansion cards (PCI-E) not working with keyboards

Hello everyone!

I’m setting up a VFIO build with a USB expansion card to pass through to the guest VMs. This works well so far, except for the fact that none of the two USB expansion cards I tried so far work well with a USB keyboard under linux (neither on host nor guest, so not an issue with VFIO).

The problem I’m observing is that some keystrokes are not registered at all, while others remain in the ‘pressed’ state after releasing, as verified by xev.

I have tried cards with the Renesas uD720201 and ASMedia ASM3142 chips, with similar results. I tried different keyboards, as well as different PCI-E slots. Tested under Arch and Ubuntu 20.04.

Does anyone have an Idea on what’s going wrong here and how I can fix it?

Try updating your motherboards BIOS. Also make sure you have a enough bandwidth to handle the amount of USB devices you are trying to run. As you could be maxing out your CPU’s PCIe lanes

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