I wrote:
I'm not sure if this is a problem with the EHCI
driver or your USB
controller,
Okay, I found two bugs in the EHCI driver that explain all your
problems. Apparently, these bugs show up only if the USB host
controller issues interrupts not for every completed microframe; you
seem to be the only one with such hardware.
I've CC'd you on the patches; holler if you need entire files.
Regards,
Clemens