Sierra dual QMI/MBIM

[Markus Gothe]

I am not using udev as hotplug-script, remember? :-).

//M

Den 27 jul 2015 9:28 em skrev Bjørn Mork <bjorn at mork.no>:
>
> Markus Gothe <nietzsche at lysator.liu.se> writes: 
>
> > Maybe Björn already mentioned this. 
> > 
> > Have USBCOMP=14 on a 340U, MBIM takes precedance when choosing default 
> > config. 
>
> Yes, that is due to Linux preferring class functions over vendor 
> specific. 
>
> > I switch it to QMI mode, I can connect etc. However no data flows on 
> > the interface. 
> > 
> > Seems like the first driver to initialize it also sets the mode 
> > temporary in fw (until reboot). 
>
> I haven't seen that exact behaviour, but I guess it's likely that some 
> firmware versions fail to initialize QMI mode after having seen the 
> MBIM/NCM commands sent by the driver during probing and setup. 
>
> My experience is that you can switch to QMI mode as long as you haven't 
> sent any MBIM commands.  But I have only verified that on one firmware 
> revision on the MC7710.  Other combinations could very well show 
> different symptoms. 
>
> In any case: The firmware is incapable of switching modes, despite the 
> multi-config appearing to allow this.  The firmware should be switched 
> to the desired mode on discovery.  Changing modes requires a firmware 
> reset and a new discovery phase. 
>
> I'd call this a firmware bug, but I'm sure the vendor would say 
> "functions as designed" :-) 
>
> > My current workaround is to assign it driver info to NULL in 
> > cdc_mbim.c... Not very convenient. 
> > 
> > Anybody knows a better workaround? 
>
> Using an udev rule to select the mode on device discovery should prevent 
> the "wrong" driver from binding to it. 
>
>
> Bjørn