Problems to get valid location data with Sierra Wireless MC7455

[Aleksander Morgado]

Hey,

> >> >> > [...] Do you have the GPS specific antenna connected to the module? Do
> >> >> > you have good satellite coverage?
> >> >>
> >> >> The GPS specific antenna is connected to the module and hopefully the
> >> >> satellite coverage is sufficient (my mobile phone tells me that it sees
> >> >> 10/27 satellites if it is held next to the GPS antenna). So I assume
> >> >> that perhaps there is some technical problem with respect to the antenna
> >> >> which should be excluded before further suspecting the software setup.
> >> >>
> >> >
> >> > Try to go outside with the hardware and get a clear sky view. If that
> >> > doesn't help either, there may really be a problem with the antenna
> >> > setup.
> >>
> >> as it did not help to have the antenna outside with a direct view to the
> >> sky I again thought about what could be wrong with my setup. Asking
> >> myself how to get the number of satellites the module sees I ended up
> >> at libqmi and hopefully tried to do the right thing here:
> >>
> >>     root at MP:~ qmicli --device=/dev/cdc-wdm0 --loc-get-gnss-sv-info
> >>     [01 Feb 2018, 02:24:11] -Warning ** [/dev/cdc-wdm0] requested auto mode but no MBIM QMUX support available
> >>     error: couldn't create client for the 'loc' service: CID allocation failed in the CTL client: Transaction timed out
> >>
> >> Could this be the root of my problems: not having configured libqmi with
> >> QMI over MBIM QMUX service? (Although I thought I did it correctly - but
> >> perhaps there is a quirk in my build system here that I would like to
> >> debug if you give me a positive answer).
> >>
> >
> > No, that's not it, you probably don't require QMI over MBIM here if
> > your device is already using QMI.
> >
> > Try to add a "-p" to that qmicli command you're using. Looks like you
> > may be trying to run QMI commands while other process (ModemManager?)
> > is also using the port. Using "-p" will direct your QMI messages
> > through the "qmi-proxy" that MM should have launched.
>
> thanks for your help, now I get
>
>     root at MP:~ qmicli -p --device=/dev/cdc-wdm0 --loc-get-gnss-sv-info
>     error: operation failed: timeout
>

Oh, maybe you just needed to explicitly start the GPS engine first?
You could try this:

$ qmicli -p -d /dev/cdc-wdm0 --loc-start
$ qmicli -p -d /dev/cdc-wdm0 --loc-follow-gnss-sv-info --loc-follow-nmea
(and wait)

> And again I have a little 'Thank you!': I stumbled across a simple issue
> in libqmi and opened up merge request [1]. Could you have a look at it,
> please?
>

Good catch, merged now, thanks :)

-- 
Aleksander
https://aleksander.es