SIM hot swap

[Aleksander Morgado]

On Fri, Feb 28, 2014 at 10:07 AM, Ben Chan <benchan at chromium.org> wrote:
> I've been looking into the feasibility of supporting SIM hot swap on a MBIM
> modem.
>
> If ModemManager observes MBIM_CID_SUBSCRIBER_READY_STATUS notifications, it
> should be able to detect when the SIM is removed, and then put the modem in
> the disabled state. If ModemManager continues to monitor
> MBIM_CID_SUBSCRIBER_READY_STATUS notifications, it should be able to detect
> when the SIM is re-inserted. ModemManager will need to recheck if the SIM is
> PIN locked when it tries to re-enable the modem. Does it make sense?
>
> I guess handling the re-insertion of SIM may not be straightforward due to
> the way that ModemManager currently handles PIN unlock (during
> initialization and not enabling) and monitors unsolicited events (only when
> the 3GPP interface is enabled). It may still be useful to handle the SIM
> removal.


I also have some modems that support this feature, at least the
SierraWireless/Wavecom FXT009 fully allows it. When the SIM is
removed, though, we need to move the modem to "Failed" state, not to
"Disabled". The "Failed" state is a state in which we only export the
basic Modem interface (well, and the Firmware one). We can allow
plugins to provide methods to be run during this Failed state, e.g. to
setup unsolicited notification handlers and the like. I don't see any
problem in adding per-plugin logic to handle the Failed state case,
but handling the modem fallback to that state when the SIM is removed
may be problematic. Anyway, yeah, fully agree that we can implement
this feature.

-- 
Aleksander
https://aleksander.es