The below seems to solve problem, but not always.
Find the driver associated to your ttyUSBx device.
user@host:/# sudo cat /proc/tty/drivers
/dev/tty /dev/tty 5 0 system:/dev/tty
/dev/console /dev/console 5 1 system:console
/dev/ptmx /dev/ptmx 5 2 system
/dev/vc/0 /dev/vc/0 4 0 system:vtmaster
usbserial /dev/ttyUSB 188 0-511 serial
ttyAMA /dev/ttyAMA 204 64-77 serial
ttyprintk /dev/ttyprintk 5 3 console
pty_slave /dev/pts 136 0-1048575 pty:slave
pty_master /dev/ptm 128 0-1048575 pty:master
unknown /dev/tty 4 1-63 console
/dev/ttyUSB uses usbserial. Now dig a little further:
user@host:/# sudo lsmod | grep usbserial
usbserial 40960 1 ftdi_sio (USB-to-serial converter is a Prolific FTDI)
or
usbserial 37173 1 pl2303 (USB-to-serial converter is a Prolific PL2303)
Find the identity of USB device:
user@host:/# sud ls -l /sys/bus/usb/drivers/ftdi_sio/
total 0
lrwxrwxrwx 1 root root 0 Dec 6 13:07 1-1.5:1.0 -> ../../../../devices/platform/soc/20980000.usb/usb1/1-1/1-1.5/1-1.5:1.0
--w------- 1 root root 4096 Dec 6 13:07 bind
lrwxrwxrwx 1 root root 0 Dec 6 13:07 module -> ../../../../module/usbserial
--w------- 1 root root 4096 Dec 6 13:07 uevent
--w------- 1 root root 4096 Dec 6 13:07 unbind
So 1-1.5:1.0 is the identifier of ttyUSB0
Disconnect the device:
user@host:/# sudo echo -n "1-1.5:1.0" > /sys/bus/usb/drivers/ftdi_sio/unbind
or
user@host:/# sudo echo -n "1-1:1.1" > /sys/bus/usb/drivers/cp210x/unbind
Unload the driver:
user@host:/# sudo modprobe -r ftdi_sio # or pl2303
user@host:/# sudo modprobe -r usbserial
Re-load the driver:
user@host:/# sudo modprobe ftdi_sio #or pl2303
Reconnect it:
user@host:/# sudo echo -n " 1-1.5:1.0 " > /sys/bus/usb/drivers/ftdi_sio/bind
or
user@host:/# echo -n "1-1:1.1" > /sys/bus/usb/drivers/cp210x/bind