Signal quality not updated with Quectel EG25 through QMI

[Aleksander Morgado]

Hey!

>
> I recently updated by system to drop ppp/AT usage for CDC. Now my EG25 dongle work through qmi-wwan driver and libqmi.
>
> But I began to experience a major difference with the old protocol method. My signal quality is not updated anymore (the information output in Status chapter of mmcli -m any stays "cached").
>
> By the way, I use ModemManager 1.16.6 and libqmi 1.28.8
>
> From what I understand by reading the code, when using ppp/AT commands, ModemManager poll regularly the signal quality but with QMI , it registers to indicator events and wait for indicator (from libqmi ? from qmi-wwan driver ? from the modem firmware ? I don't know yet)
>

The indications would be sent by the modem firmware itself. The idea
is, we register for those indications, I think we ask the module to
report signal quality changes under a certain range, and then wait for
those indications.

>
> I see this worrying log in ModemManager debug log:
>
> ModemManager[1369]: <debug> [modem0] extended signal information reporting disabled (rate: 0 seconds)
>

This is the support for the "extended Signal interface":
https://www.freedesktop.org/software/ModemManager/doc/latest/ModemManager/gdbus-org.freedesktop.ModemManager1.Modem.Signal.html

This is an optional feature that if needed, it should be explicitly
enabled. It allows users to e.g. monitor RSSI/RSCP/RSRP...

For normal usage, in order to receive a value of the signal quality
that is independent to the access tech in use, we have the
"SignalQuality" property, which gives the value in percentage.

>
> And I only received one signal quality value after that, this is completely silent.
>
> This seems logical (even I don't know why the refresh rate is set to 0 by default) and I manually set the refresh rate with mmcli -m any --signal-setup=30 but this doesn't change anything and the signal quality keeps being not updated.
>
> I checked that via the signal quality in mmcli output which state in "cached" state while running mmcli -m any --signal-get gives info that are updated.
>

But what do you want? Do you want the extended signal interface
information, or do you want the percentage value (which is probably
what you were using when AT protocol was being used).

> Do you know where the problem came from (the 0 default refresh rate and the not updated signal quality) ?
>

So, the 0 default refresh rate is expected. The optional Signal
interface is disabled by default.

The missing updates in the signal quality, well, we need to see
whether the EG25 reports those or not. Have you done tests e.g.
disconnecting antennas and such, to see if those indications are
emitted? Maybe the module is sending the new "Signal Info" indications
(which we don't process automatically) instead of the "Signal
Strength" ones? If possible, please debug that with MM debug level
enabled and also with the qmi-proxy running in verbose mode (in case
the problem is a failure in the indication forward done by the proxy).

Cheers

-- 
Aleksander
https://aleksander.es