Modem SORACOM (SC-QGLC4-C1) : Unable to find a usable modem character set

Aleksander Morgado aleksander at
Sat Dec 19 09:40:32 UTC 2020


> After a sim was inserted in the dongle, no problems have been notices so I it seems that a missing sim prevent modem initialization (which, to my opinion should not be , it should failed only on enable step).

Yes, I agree. If the CSCS=X operation fails, we should still go on,
maybe assuming a default charset encoding. For this specific setup,
the modem will end up in failed state anyway, so it would be fine.

> Nevertheless, I open a bug ( to track the mmcli segfault on a badly initialized modem and I'll try to come up with a MR to fix this (I don't know yet if the real fix should be to not expose the modem on DBus when it is not initialized or simply add a null-protection somewhere in mmcli)

The real fix is in ModemManager daemon; it looks like the daemon is
publishing a MM object in DBus, BUT which does NOT implement the
"Modem" interface, and that is completely wrong. The MM objects in
DBus must always implement the "Modem" interface. That said, yes,
mmcli can also be improved so that we don't just assume the "Modem"
interface always exists in the MM objects. If you're up to fixing
this, the problem is that mmcli is assuming the return of
mm_object_peek_modem() or mm_object_get_modem() is always non-NULL.


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