Problems to get valid location data with Sierra Wireless MC7455

Ulrich Ölmann u.oelmann at
Wed Sep 26 07:49:07 UTC 2018

Hi Aleksander,

Aleksander Morgado <aleksander at> writes:
>> >> > [...] 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

I think I will not investigate further here, but leave it at that for
the moment.

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,

Best regards

Pengutronix e.K.                           | Ulrich Ölmann               |
Industrial Linux Solutions                 |  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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