For the time being the 5.8 kernel has issues with Renesas USB controllers due to a FW version check issue. My PCIe x4 USB 3.0 controller card is affected by it. I need that controller working, as I currently have a USB HDD enclosure attached to it, that I need to use.
It’s currently being discussed here and the latest solution is to remove that check entirely because it turned out there are so many FW versions in the wild (FW version 8209 in my case). I’m currently trying to build a 5.8 kernel with the patch added using the latest PKGBUILD from GitLab (5.8.1-3 at present). However, as of yesterday I wasn’t able to compile a new kernel due to a patch (
0001-nonupstream-navi10-vfio-reset.patch) cannot be correctly applied (and it does matter to me as I’m using a 5700 XT on that system). The current stable 5.8 kernel is 5.8.0, though.
So for the time being using the 5.8 kernel isn’t a good idea if your system has Renesas USB3 controllers. I have to stay on 5.7 for the moment until I could get a modified kernel built.