libqmi compatible with Quectel RM520N-GL (quectel driver qmi_wwan_q, or is standard driver needed)? Multiple parallel connections...

[Aleksander Morgado]

Hey,

>
> I thought I try Quectel delivered driver next.
>
> I compiled/installed it, used their Connection Manager quectel-CM and
> after some changes (especially dhcp), I was able to build up a
> connection and ping remote side via IPv4.
>

What changes did you require in DHCP?

> So now, back to original step, try libqmi (proprietary quectel driver
> still in use):
>
> $ sudo qmicli --device=/dev/cdc-wdm0 --device-open-qmi
> --wds-get-channel-rates
> [15 Aug 2023, 16:02:21] -Warning ** [/dev/cdc-wdm0] couldn't detect
> transport type of port: unexpected driver detected: qmi_wwan_q
> [15 Aug 2023, 16:02:21] -Warning ** [/dev/cdc-wdm0] requested QMI mode
> but unexpected transport type found
> error: couldn't create client for the 'wds' service: CID allocation
> failed in the CTL client: Transaction timed out
> $ sudo qmicli --device=/dev/cdc-wdm0 --device-open-proxy
> --wds-get-channel-rates
> [15 Aug 2023, 16:02:58] -Warning ** [/dev/cdc-wdm0] couldn't detect
> transport type of port: unexpected driver detected: qmi_wwan_q
> error: couldn't open the QmiDevice: Cannot automatically select QMI/MBIM
> mode
> $
>
> Ok, now I am a bit lost, which way to go:
>
> Can qmicl be used together with quectel driver and I just need to ignore
> warnings and change some settings?
>

You can basically ignore the warnings but make sure you select the
port in QMI mode. libqmi doesn't know anything about the quectel
proprietary driver.
You can use --device-open-qmi to silence those warnings.

> Or must I deinstall quectel proprietary driver to get libqmi working again?
>
> Does libqmi and standard qmi wwan driver support multiple parallel
> connections? As far as I have seen, libqmi seems to supports it.
>

Yes.

> Do I need to tell the quectel modem somehow to enable more than one
> connection? Or some parameter/setting for standard driver needed?
>

If you want to use QMI for multiple PDNs you need to run
--wds-bind-mux-data-port with the correct settings. Not sure I have my
own example around right now, but you can also follow the connection
sequence implemented in ModemManager in mm-bearer-qmi.c to see what it
would look like. Here you may also have an example, maybe it's just
what you need: https://techship.com/faq/example-on-how-to-establish-a-data-connection-with-telit-fn980-series-in-linux-using-qmi-rmnet-and-usb-interface/

> For my info: Shall I see more than one /dev/cdc-wdm? Or all done via
> this single entry point/device?

For newer modems, a single /dev/cdc-wdm port is the most common case.
You can do multi-PDN and have a single /dev/cdc-wdm port just fine.

Cheers!

-- 
Aleksander