Re: ModemManager (qmi_wann / qcserial) and gpsd

[Dan Williams <dcbw redhat com>]

On Wed, 2017-05-17 at 21:28 -0600, Phil Daum wrote:
> Hi Dan,
>
> Now that I had a 3G connection working on my Sierra Wireless MC7354
> (thanks
> to you), I would like to utilize the on-board GPS.  I was wondering
> if I
> could ask you a general question:
>
> Is the use of gpsd compatible with the use of ModemManager using
> qmi_wann
> and qcserial?
>
> The reason I ask is that I have source code utilizing the gpsd API
> which I
> would like to continue using.

If the device provides a couple serial ports alongside cdc-wmd0, then
one of them may be a GPS port as is common with Gobi-based devices.  So
you may be able to follow these directions:

http://www.thinkwiki.org/wiki/Qualcomm_Gobi_2000#GPS

and get it to work with the 7354 too.  ModemManager gets location info
through the QMI interface, not the AT serial port, so it should not
conflict with your parallel usage of the GPS tty.

If the device doesn't provide the standalone GPS tty, then you'd have
to modify your workflow to use ModemManager's location API instead,
which does have the ability to output text-based GPS strings, but does
so through the D-Bus API rather than a serial port.

Dan