Comment 9 for bug 1878602

> Is there any USB3 device connected at all?
No. Only a Thunderbolt Dock is connected.

> Just stays in disabled/Disconnected, as if no device is connected.
Because there's no device connected to it. Actually it seems to be completely unused.

I wonder if we can disable the Bus 01/02 xHC completely, since all internal USBs are connected to the other xHC:
$ lsusb -t
/: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/6p, 10000M
/: Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/12p, 480M
    |__ Port 5: Dev 2, If 0, Class=Vendor Specific Class, Driver=, 12M
    |__ Port 9: Dev 3, If 0, Class=Video, Driver=uvcvideo, 480M
    |__ Port 9: Dev 3, If 1, Class=Video, Driver=uvcvideo, 480M
    |__ Port 9: Dev 3, If 2, Class=Video, Driver=uvcvideo, 480M
    |__ Port 9: Dev 3, If 3, Class=Video, Driver=uvcvideo, 480M
    |__ Port 9: Dev 3, If 4, Class=Application Specific Interface, Driver=, 480M
    |__ Port 10: Dev 4, If 0, Class=Wireless, Driver=btusb, 12M
    |__ Port 10: Dev 4, If 1, Class=Wireless, Driver=btusb, 12M
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 10000M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 480M

External USBs and Thunderbolt are also connected to Bus 03/04.