usb: dwc2: Disconnecting hub from rpi leads to errors

[Stefan Wahren]

Hi,

i have a Cherry G83 USB Keyboard connected to external 4 Port USB hub and this
is connected to a Raspberry Pi B (Linux 4.4-rc7).

If i disconnect the USB hub from the Pi, i will get multiple of this message:

[  103.558379] dwc2 20980000.usb: --Host Channel 1 Interrupt: Transaction
Error--
[  103.558639] dwc2 20980000.usb: --Host Channel 6 Interrupt: Transaction
Error--
[  103.558709] dwc2 20980000.usb: --Host Channel 7 Interrupt: Transaction
Error--
[  103.558771] dwc2 20980000.usb: --Host Channel 3 Interrupt: Transaction
Error--
[  103.558871] usb 1-1.2: clear tt 1 (9051) error -71

If i reconnect the USB hub everything works as before.

If i replace the Raspberry Pi B with a Olimex Olinuxino iMX233 Maxi (Chipidea
USB) the errors doesn't occure after disconnecting the hub. So i assume this
issue is specific to dwc2 or Raspberry Pi. This issue doesn't look like a
regression. 

The output of dmesg and lsusb -v can be found on gist [1].

Best regards
Stefan

[1] - https://gist.github.com/lategoodbye/dd04293078f2d8afbf73