Can not change speed of ttyUSB0 on BBB - using 3G modem

Hi,

My USB 3G modem (Huawei E156) is connected to beagle bone black.

I noticed long ping times (from 4 to 30 seconds!) and low speed (9kbps). No package lost %.

Discovered that the problem is that the /dev/ttyUSB0 device is set up for 9600bps.

Tried with the 4 combinations that I had available: ubuntu with kernel 3.8.13; debian with kernel 3.13.9; BBB revision A6 and BBB revision B; I have 5 identical modems, already tried 2 of them, same problem.

`

stty -F /dev/ttyUSB0 speed

9600

stty -F /dev/ttyUSB0 115200

stty: /dev/ttyUSB0: unable to perform all requested operations

stty -F /dev/ttyUSB0 speed

9600

`

By looking at /sys/kernel/debug/usb/usbmon/0u I can see that usb speed is truncated at 9600bps.

Using the same modem in my notebook (intel i7 x64 PC / Ubuntu kernel 3.11), all works as expected; I have high speeds on /dev/ttyUSB0 and it works as expected.

Any hints about how to solve this?

Thanks in advance,