workarounds required to use U301/CMO6008/16d8:6008 USB CDMA modem with modern Linux kernel and ModemMamager
Submitted by Wladimir Mutel
Assigned to ModemManager bug user
Description
Dear maintainers,
I created Ubuntu bug at https://bugs.launchpad.net/ubuntu/+source/modemmanager/+bug/1525392 where you can find most of my findings on this topic. In short, to use this quite old modem (with firmware from y.2008), you need to blacklist qmi_wwan and cdc_wdm modules from loading into [modern] Linux kernel. Else, if these modules are loaded, ModemManager recognizes this modem as something new with QMI interface, and then complains about too small versions of some QMI services ('nas' and 'dms'). The same modem works well in usb/option mode under Ubuntu 12.04, but stops working under Ubuntu 14.04 and Debian 8.2 until you blacklist these modules. I am not sure where this should be fixed, at Linux kernel level or at ModemManager's, but in my view, subjecting a plain Linux user to blacklist new modules to keep compatibility with older modem is just unpleasant experience.
Please direct me to contact with appropriate Linux kernel developers if you see this way as more reasonable. Or is it reasonable to support older QMI nas/dms versions in ModemManager ?
Version: 1.4