Modem not resetting.

[Aleksander Morgado]

Hey,

> Hi, I see an issue when resetting modems, both with Telit and Sierra. It happens quite rarely but renders the modem unusable. I tell the modem to go offline and then to reset, most of the time this works, it's a standard thing. Occasionally it will say that it is a success but never actually reload, no matter how many times you issue the commands after this the modem won't reset, and it also can not come back online (invalid transition I assume). Here is the verbose output if that helps in any way, any test you thinkI can run while I have a modem in this state? (Telit LNM960A18)
>
>
> I’ve run into this before with MDM 9207 modems from Telit and Quectel, but only when the AT&T MBN (carrier profile) is activated. Other carriers profiles did not exhibit this behavior.
>
> I worked around the problem by skipping the “offline" mode step and just sending a dms_set_operating_mode message with QMI_DMS_OPERATING_MODE_RESET. See an implementation here:
>
> https://github.com/temperednetworks/ModemManager/blob/752027d19f77e65b1d4568de49cf2599c49d4e9e/plugins/quectel/mm-broadband-modem-qmi-quectel.c#L198
>
> I’m hesitant to upstream this because I know that some older qualcomm chipsets return InvalidTransition when setting the operating mode to QMI_DMS_OPERATING_MODE_RESET without first setting it to QMI_DMS_OPERATING_MODE_OFFLINE.
>

If that is the case, we could always try RESET first, and if we get
InvalidTransition, fallback to OFFLINE+RESET. That wouldn't harm I
think.

-- 
Aleksander
https://aleksander.es