FCC Authentication with umbim

[Bjørn Mork]

Fabian Schörghofer <fabian.schoergi at gmail.com> writes:

> Hi,
>
> I have an EM7455 here from or better with Lenovo settings applied. How
> to deactivate the FCC check? The device will not be used in a Lenovo
> laptop anymore, so no problem with the notebook not be booting anymore.
>
> Bjørn wrote that the FCC_AUTH can be deactivated in the settings:
>
> https://lists.freedesktop.org/archives/libmbim-devel/2016-April/000704.html

I shouldn't have written that :) It seems very likely, but we don't
actually *know*.

>> learn a bit about these modems, and I did notice that there is a
>> 
>>  FCC_AUTH => 01
>> 
>> setting in the
>> 1102662_9905046_EM7455_02.05.07.00_00_Lenovo-Laptop_001.003_000.nvu
>> file (which AFAIU contains all the Lenovo specific settings). 
>
> How can this be achieved? Is there a "settings editor"?

I assume there is, but I've never seen one. It is either a tool provided
to OEM vendors, or maybe just an internal tool for Sierra.  What I
observe is that laptop vendors like Lenovo and Dell include such .nvu
files as part of their driver/firmware packages. 

Now I have been fiddling a bit with the files to try to understand the
format, and had some success with creating similar files.  But there is
a lot I don't know, so any experiment has a significant chance of
bricking the modem.  Personally I don't think it's worth the risk for a
modem you are not prepared to replace...

> I know this might be the wrong place to ask,

The OpenWrt or LEDE developement lists would probably be better, but I
haven't seen anyone here have a problem with a few umbim discussions.
libmbim and umbim are so different that it's not like they really
compete in any way.  They solve different problems.

> but if the above is not
> possible, would it be possible to send the FCC Auth with umbim? The
> library hasn't been updated recently, so I don't think this is as of now
> possible.

Implementing this in umbim is on my TODO list.  Which means that I might
do it in a couple of years :)

I don't think it makes sense to add the full QMI proxying thing in
umbim, since there is no matching libqmi library.  A simpler approach,
just implementing the necessary QMI messages inside umbim, is probably
fine.  Should not be too much work if anyone wants to get their feet
wet. I think it would be good for umbim if it got more developer action
than an occasional patch from John or me..  Especially since I don't use
umbim myself, except for testing.


Bjørn