MC7455 location support

[Dan Williams]

On Wed, 2017-04-12 at 13:21 +0000, Karoly Pados wrote:
> Hello,
> 
> I have a MC7455 form Sierra Wireless. It is working fine for data
> communication, but ModemManager doesn't seem to be able to recognize
> the locations services (GPS and A-GPS) provided by the modem. 
> 
> mmcli -m 0 --location-status
> 
> /org/freedesktop/ModemManager1/Modem/0
>   ----------------------------
>   Location |   capabilities: '3gpp-lac-ci'
>            |        enabled: '3gpp-lac-ci'
>            |        signals: 'no'
> 
> If I start ModemManager with the --debug flag and then issue AT-
> commands using --command by hand, I can get a GPS fix and retrieve
> the location using raw AT commands. (This also means that in my case
> there is no need to unlock location services using a password.)
> 
> I read on this list that the modem needs to be in QMI-mode for MM to
> support location data. I think this is already the case because when
> I start MM in debug mode I can see it is using QMI to communicate.
> 
> Is there anything else I can do or need to check to make location
> data in MM working? Or any way I can help to implement support for
> it?

At the moment, no.  The device is likely in MBIM mode which is why you
don't get location data.  There are two options we are exploring for
ModemManager:

1) use the MBIM QMI passthrough to provide the location data that QMI
can provide, which will work with this device because it's a Qualcomm-
based one

2) if that fails, see if we can use the AT ports for GPS

This is mainly just a problem for MBIM devices, because the MBIM
protocol specification does not contain any GPS-related options.  That
is left to vendor proprietary methods, as you've discovered :)

So TLDR; you can't do this yet but it's at least being thought
about/worked on.  If you're interested in helping fix this, we can use
either code or testing...

Thanks!
Dan

> My software:
> # uname -a
> Linux a13-olinuxino 4.9.21 #2 SMP Mon Apr 10 10:29:48 CEST 2017
> armv7l GNU/Linux
> # ModemManager --version
> ModemManager 1.6.2
> ...
> # qmicli --version
> qmicli 1.16.0
> ...
> 
> 
> Thank you for your help, greetings,
> 
> Károly Pados
> 
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