(In reply to Stanislav Brabec from comment #13) > Looking at strace log, it seems that brltty indeed does a probe, but it > loops forever on a bare CP2101 device. And if I kill brltty, device remains > in an unusable state (/dev/ttyS0 does not exist). Can you create a backtrace, to get an idea which device/brltty driver is misbehaving? The driver likely uses libusb to detach the kernel driver, but fails to reattach in case it is forcefully killed.