Permanently set modes for QMI modem

[Aleksander Morgado]

Hey

>
> When trying to set the allowed modes (4G only in my case), the setting
> doesn't seem to persist across power-cycles of the modem. Is there a way
> to make this setting permanent or reset it every time the modem state
> machine is brought up by ModemManager (perhaps a simple external script,
> but when to run it?)? My modem is a Quectel EG91-E and ModemManager is
> using the QMI interface.
>

There was a recent issue about this as well:
https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/580

There's a TLV in the "NAS Set System Selection Preference" named
"Change Duration" (0x17), which we set to
QMI_NAS_CHANGE_DURATION_PERMANENT (the other value supported is
QMI_NAS_CHANGE_DURATION_POWER_CYCLE). Unless we're doing something
wrong, I think this is the way to ask for a permanent change, so not
sure what else we could be doing.

-- 
Aleksander
https://aleksander.es