Re: [RfC] Retry registering packet radio to home PLMN when available.

[Denis Kenzior <denkenz@gmail.com>]

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Hi Andrew,

> One reason you might want to not register to network would be for power
> saving.

Sure, but remember there are two cases here:

The device oFono is managing is a proper voice + data modem.  In which case 
the likely scenario is that we want to always be registered to the voice 
network and not register to GPRS network for power reasons.

The second case is we're managing a GPRS-only data device.  In which case the 
power considerations are flipped.

>
> It seems like a small gain for adding this dependency (which will seem
> especially strange to users not knowing about this quirk we're relying
> on).  The current picture is that we want to have an indication of
> when we might be able to register back to home PLMN with gprs.  We
> keep the gprs radio disabled and enable the circuit-switched radio
> possibly with the only aim being to have that (possibly weak)

For the devices that oFono is primarily targeting (e.g. voice + data devices) 
this behavior is exactly what we want, no?

> indication.  Couldn't we instead use the gprs radio for the same
> purpose?  We would simply prohibit activating contexts while roaming
> and we would report Attached = false on D-Bus.

I agree that we want to do this for data-only devices.  In which case I 
suspect we need to have the driver tell oFono that it is a data-only device.  
With implications that we always auto-attach, and either ignore RoamingAllowed 
setting completely or do as you suggest and refuse to activate the context. 

The tricky part is how to report the operator.  Remember that it is quite 
ambiguous what COPS=0 does.  On some devices it activates CSD radio.  On some 
GPRS, and both on others.

Regards.
=Demos