Randomly the usb hub port is disabled and the device (usb camera) is not accessible until the system is re-powered. The 
only message in the system log is:
Jan 21 12:36:50    2    12     0 hub_transfer_done: hub (busno 1, devno 4, vid 0x0424, did 0x2517) - port 1 disabled
Jan 21 12:36:50    2    12     0 hub_transfer_done: hub (busno 1, devno 4, vid 0x0424, did 0x2517) - port 1 disabled
Jan 21 12:36:50    2    12     0 CLASS_PortDisabled: port 1

The usb server is started as:
       io-usb -v -dehci -dxhci  

The system usb configuration is attached.

Any idea or root cause why the driver is disabling the hub port ?

Regards,
Janusz