Can't connect using ModemManager when modem is in QMI mode

[Aleksander Morgado]

Hey

> > I am revisiting this with a little more information, and a better
> > understanding of what you wrote.
> >
> > A simple-connect from ModemManager always fails. I can always connect
> > from qmicli (Abbreviated log below; stripped out raw data in this
> > trace)
> >
> > But as you say, when connecting via ModemManager, the modem sends
> > indications that the Preferred Data System goes to 'unknown' and the
> > ps_attach_state goes to 'detached'
> >
> > Is there any way to manually turn on indications and monitor them from
> > qmicli or get ModemManager to ignore these indications just to see if
> > it's just a bug in the modem firmware? Could there be some other
> > initialization of the modem by ModemManager that triggers this
> > behavior?
> >
> > Jeff
> >
> > root at wwan:/$ qmicli -d /dev/cdc-wdm0 --wds-start-
> > network=apn='broadband'  --client-no-release-cid
>
> I see you have --client-no-release-cid however:
>
> [12 Jan 2022, 01:23:09] [Debug] [/dev/cdc-wdm0] Releasing 'wds' client
> with flags 'none'...
> [12 Jan 2022, 01:23:09] [Debug] [/dev/cdc-wdm0] Unregistered 'wds'
> client with ID '36'
> [12 Jan 2022, 01:23:09] [Debug] Client released
> [12 Jan 2022, 01:23:09] [Debug] Closed
>
> which would terminate the data connection... not sure what the solution
> is, but that's likely the cause.
>

Those debug messages are a bit misleading; the client CID is not being
released because the qmi_device_release_client() receives NONE as
flags (as per the log). The client CID would be really released in the
device id RELEASE_CID was received instead. So that interaction above
is really ok, the --start-network with --client-no-release-cid is not
implicitly releasing the client CID in the device.

-- 
Aleksander
https://aleksander.es