mvebu_u3d: USB3.0 device mode not working properly

[mmgu]

While testing linux-4.4.52-armada-17.08 on our Armada-7040 based board, we found g_mass_storage module can only work for the first time. Just run the following command after booting up:

# modprobe g_mass_storage file=/dev/sda

The host side (Windows PC) recognized USB mass storage device successfully.

If we try to unload g_mass_storage module and load it for a second time, system either crashes or USB device can not be recognized by host. If USB cable is left connected when we do rmmod g_mass_storage, kernel will crash. If we disconnect USB cable and then rmmod g_mass_stroage; modprobe g_mass_storage file=/dev/sda, the Windows host will report "unrecognized USB device" error.

'dmesg' shows:

[ 1217.560142] USB device: connected
[ 1218.404488] USB device: warm reset
[ 1219.036488] USB device: warm reset
[ 1219.667488] USB device: warm reset
[ 1219.780754] USB device: suspend

Disconnecting/reconnecting USB cable won't help; however, it will work if we connect a USB2.0 cable.

[smurfix]

Any feedback on this problem – or is this issue tracker a black hole?