Rpi USB check-list

rpi-update smsc95xx.turbo_mode=N in /boot/cmdline.txt dwc_otg.microframe_schedule=1 in /boot/cmdline.txt vm.min_free_kbytes=16384 in /etc/sysctl.conf reboot rm /var/log/kern.log /var/log/kern.log.1 /var/log/kern.log.*.gz shutdown -r now lsusb -v | grep -iP "Transfer Type.*(Interrupt|Isochronous)" | wc -l cat /var/log/kern.log | grep -iP "fail|warn|error" | perl -p -e 's/^[^\]\n]*\]//g;s/(warn_alloc_failed: )[0-9]+/$1/g' | sort -u; dmesg
 * 1) 5VDC 1A+ power supply
 * 2) low resistance power cable test
 * 3) powered USB hub 2 or less
 * 4) power Isolated USB cable link
 * 5) There are some known known bugs with the usb driver, try:
 * 1) check and add your device to RPi_VerifiedPeripherals
 * 2) google search part of the bug report link
 * 3) bug report:
 * 1) make the error happen