[RFC] Unmanaged GPS setup / location source

Aleksander Morgado aleksander at aleksander.es
Sat Jun 28 09:08:36 PDT 2014

On Fri, Jun 27, 2014 at 5:45 PM, Dan Williams <dcbw at redhat.com> wrote:
> On Fri, 2014-06-27 at 10:51 +0200, Aleksander Morgado wrote:
>> Hey,
>> I've been asked whether it would make sense to allow having
>> ModemManager control the status of the GPS module in a device, *but*
>> leaving the tty where the NMEA traces are dumped untouched. This would
>> allow to integrate with other standard GPS applications which read
>> from a tty, while leaving MM the control over when to enable/disable
>> the GPS module.
>> Any comments on this?
> I haven't looked at the code yet, but the approach seems OK.
>> I have a draft implementation (mmcli commands not yet done) already in
>> the 'aleksander/gps-unmanaged' branch in upstream git, where I just
>> define a new MM_MODEM_LOCATION_SOURCE_GPS_UNMANAGED source. When this
>> source is enabled, GPS module is started but the GPS tty is not used.
>> Of course, the implementation also forbids trying to enable unmanaged
>> and raw/nmea GPS at the same time. Also, currently only done for
>> Option/HSO (the only plugin which does GPS over a tty for now). I may
>> add GPS support for Cinterion one of these days as well.
> Gobi! :)  The fun thing here is that you have to open the port and run
> $GPSSTART or something like that, then it starts spewing NMEA, and to
> stop it you  have to re-grab the port and run $GPSEND.  I guess that
> would be fun if the port is still locked by the consumer.

You mean you need to send $GPSSTART in the same port where you're
going to get the NMEA traces?

> Also, I think the Ericsson devices do raw NMEA to a TTY too.

Yes, I meant to add support for it earlier, but I don't have a module
to test with.


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