Modem SIMCom SIM7600 failed

[Herve Patriarche]

Hey Aleksander

On 17/01/2020 09:56, Aleksander Morgado wrote:
> Hey,
>
>> Using ModemManager (version 1.10.8) with modem SIMCom SIM7600G, it
>> failed to probe it at boot time.
>> If I stop ModemManager and wait a while and then restart it probes it
>> better.
>> With newest modem firmware it is ok. But I wonder why ModemManager do
>> not re-probe it and it failed ?
>>
> Looks like the device was not able to reply to any QMI message during
> the first initial 20s after bootup:
> Jan 16 11:19:15 ws-box-v1.1 ModemManager[176]: <debug>
> (usbmisc/cdc-wdm0) error checking QMI support: 'Transaction timed out'
>
> I guess we could still update this value even more so that the probing
> attempts end up taking longer.
>
> Is this issue happening consistently? Or did it happen randomly?
This is consistently and mainly related to firmware version of the modem.
We are in contact in parallel with SIMCom to get proper explanation.
>
> Would you be able to update the timeout to a value greater than 20s,
> e.g. 30s, and see if that solves the problem? The change would be
> equivalent to this one:
> https://gitlab.freedesktop.org/mobile-broadband/ModemManager/commit/a73b13b67cd1987431f92ea6a4ccc2cb85c51cc7
Thanks for pointing this patch. I could change the retries value and get 
the modem working.


Still a question, where could I redo the probing at the end of the probe 
loop if not device was found ?

Thanks, Herve.