Problems on a debian install that each time I plugged in a C270 the usb hung.

A look at logs showed two symptoms. lots of
usb 3-6: 3:1: cannot get freq at ep 0x86
and multiple instances of udevd also lsusb would hang.

Reason is the audio, quick fix is to unload usb audio module
rmmod snd_usb_audio so later today I may get round to writing a udev rule,