Strange behavior with ZTE MF821D (and possible other MDM9200 devices)

[Bjørn Mork]

Kristian Evensen <kristian.evensen at gmail.com> writes:

> We are currently facing a USB problem that we have not been able to
> solve. A USB ACK is not sent and the following messages appear in the
> kernel logs:
> Thu Nov 21 09:44:53 2013 kern.err kernel: [  490.600000] qmi_wwan
> 1-1.1.2:1.4: nonzero urb status received: -71
> Thu Nov 21 09:44:53 2013 kern.err kernel: [  490.600000] qmi_wwan
> 1-1.1.2:1.4: wdm_int_callback - 0 bytes

The most likely cause of this is a modem firmware crash.  I don't think
there is much you can do about that, except trying to avoid the
situations which causes the crash or getting another modem.


Bjørn