Handling QSS unsolicited in power state transitions

[Aleksander Morgado]

On Tue, Aug 1, 2017 at 4:40 PM, Carlo Lobrano <c.lobrano at gmail.com> wrote:
> It seems that sometimes the decision to send the #QSS=0 is taken with some
> delay (with HE910) and in these cases it arrives quite late (10-13 seconds)
> and disabling the notifications and then re-enabling them later does not
> avoid it.
> Considered this, I would go with ignoring #QSS unsolicited between +CFUN=4
> and +CFUN=1. The vast majority of telit modems switches the SIM off so this
> unsolicited is expected (actually, only the latest LE910 V2 FW do not do
> that) and, of course, it's the only one we will receive 'till +CFUN=1.
> Moreover ignoring QSS requires a lot less code than disabling/enabling its
> emission.
>

This is getting a bit out of hands :)

So, yes, if the module powers off the SIM slot during CFUN=4 we won't
get #QSS events, that's understandable. But... what would happen if we
go to low power mode and switch the SIM card with a different one? We
would be gettting #QSS=1 later on after CFUN=1 and we would assume
nothing had happened, and that would be wrong as the SIM is different.

Note that this issue is again unrelated to the actual hot sim swapping
logic implemented; but now that we're starting to support hot sim
swapping, we should probably also check that usecase. At the end Telit
isn't the only module that may power off SIM Card during low power
mode.

So, how about a manual check to validate whether the SIM is different
or not?, e.g comparing whether the old property values we got before
the low power mode are still the same ones now after the power up...

-- 
Aleksander
https://aleksander.es