RE: [PATCH 0/2] Add Suspended property to GPRS
Hi Marcel,
From: ofono-bounces(a)ofono.org
[mailto:ofono-bounces@ofono.org] On Behalf Of ext Marcel Holtmann
> The isimodem driver will currently suppress changes in the
> property value for short-lived suspended states caused by SMS
> transmission or other signalling. It would also be possible
> to do the suppression in the oFono core in a generic way.
> Alternatively, all the state changes and their reasons could
> also be exposed to oFono clients. However, my feeling is
> that the information might not be available in a sufficiently
> coherent way from the different modems. Anyway, I'm open to
> suggestions.
we had a brief discussion about this some time ago. And I don't think
that we can do anything than give the clients (UI and ConnMan) and
indication that the suspend has happened right now. In
general it is too
late anyway. Since making a voice call and sending a SMS are decisions
by the end user. And he/she wants to execute them right now. So it is
expected that GPRS gets suspended.
Yes, I agree, there's no sane way to provide pre-warning. A signal that
comes after the fact still has some potential uses, though:
- a hint for internet connection management to start looking for an
alternative access, in case GPRS is not back shortly
- a signal for mobile-aware applications to adjust their behavior
- UI notification for the end user
I do agree that we should not blindly tell the clients suspended if
we
now that it is a short lived situation like SMS. My personal
preference
here would be that this is done inside oFono core and the
hardware just
signals suspend (if it actually supports such notifications).
So how much work would it take to do the delay in the core?
Not that hard, I guess. We could define a suspend cause code that gets
notified to the core, based on which the core would either modify the
property immediately or start a guard timer. Perhaps something along
the lines of:
enum gprs_suspend_status {
GPRS_SUSPENDED_DETACHED,
GPRS_SUSPENDED_SIGNALLING,
GPRS_SUSPENDED_CALL,
GPRS_SUSPENDED_NO_COVERAGE,
GPRS_SUSPENDED_UKNOWN_CAUSE,
GPRS_AVAILABLE,
};
src/gprs.c:
void ofono_gprs_suspend_notify(struct ofono_gprs *gprs,
enum gprs_suspend_status status)
{
...
}
The cause code could also be exposed in the DBus interface.
I know, that
the ISI modem is more sophisticated protocol, but we do have AT modems
that have a bit harder time gathering all the information.
AT modem drivers could use any subset of the above causes.
To allow opt-in implementation in the drivers, the core could
automatically change the status between GPRS_SUSPENDED_DETACHED
and GPRS_AVAILABLE based on attach/detach notifications.
I can redraft the patches to do this. I don't really have a clue
what kind of vendor extensions are available for this in AT modems,
though. Any examples would be helpful.
Br,
MikaL