Hi,
I'm using the new Lenovo T420 port on gerrit[1] and found a bug about USB(in my post on the gerrit page). And just now I found a work around on this issue.
First I tested a USB disk on the buggy USB port before suspending the system, it works fine. Then I unplugged the USB disk, suspended my system, resume, and replugged the disk, the bug occurred. Then I unplugged the disk, reload the ehci_pci module as follows: