The mobile broadband worked ok with 3.7.x and 3.6.x, but if I enable the CDC MBIM module it no longer works. Setting the CONFIG_USB_NET_CDC_MBIM=n makes it work again. At least Fedora 18 now ships 3.8.1 with this module enabled and luckily/unluckily I answered it m during my oldconfig.
very, happens every time
Steps to reproduce:
1) try to bring up a network connection
Interface wwan0 is brought up but it doesn't get an IP. all I see in tcpdump are some DCHP queries without an answer.
The device in question:
Bus 003 Device 018: ID 0bdb:1926 Ericsson Business Mobile Networks BV
System is a fully updated Fedora 18 running on Lenovo Thinkpad X1.
I tried mainline 3.8.2 with CDC NCM and CDC MBIM both as modules, didn't work.
I disabled the new CDC MBIM and it works again.
I tried the latest fedora kernel 3.8.1-201.fc18.x86_64, didn't work.
Older fedora and mainline kernels worked ok.
Yes, this problem is known and I have a proposed hackish solution/workaround here:
It's not beautiful and I was really hoping for some feedback saying "That's stupid, why don't you just <fill in obvious and simple solution here>". But it seems I won't get any...
The current situation is of course unacceptable, so I guess I'll just have to submit that patch formally if nothing else comes up. You should be able to choose either cdc_ncm or cdc_mbim for devices like this one, implementing both protocols as different altsettings on the same interface.
A patch referencing this bug report has been merged in Linux v3.9-rc4:
Author: BjÃ¸rn Mork <email@example.com>
Date: Thu Mar 14 01:05:13 2013 +0000
net: cdc_ncm, cdc_mbim: allow user to prefer NCM for backwards compatibility
I tried it against v3.8.4 after I noticed gkh had accepted it into stable, too. And indeed that fixes the regression.
For the record, the module parameter still needs to be set to false for the old behaviour to be maintained, e.g. something like
options cdc_ncm prefer_mbim=N
to /etc/modprobe.d/cdc_ncm.conf will do the trick.