ModemManager and Quectel RM520N-GL

[Aleksander Morgado]

On Wed, Mar 15, 2023 at 12:28 PM Peter Naulls <peter at chocky.org> wrote:
>
> On 3/6/23 02:40, Patrick Kosiol wrote:
> > Hi Peter,
> >
> > Thanks for the info.
> >
> > Actually, the lsusb output was incomplete. It looks like the one attached so the
> > device is actually there. Yet, you are right, the /dev/ttyUSB device is not
> > present.
> >
> > I checked the state of the usb device and it appears to be loaded with the
> > qmi_wwan driver, which seems correct:
> >
> 80M
> >
> > Do you happen to have any other suggestion?
>
> I did, in the bit you didn't quote - this is why good quoting is always good
> practice:
>
>
> "I'm not seeing the USB serial devices for your modem, i.e, /dev/ttyUSBx.  It
> may be that you need a usb_modeswtich invocation.  ModemManager won't pick it up
> until these exist."
>

There is no need for USB modeswitch in this case though, that's
totally unrelated.

The TTYs are exposed in the USB layout (interfaces 0-3), but they are
not bound to any kernel driver. Likely the option kernel driver in use
doesn't have them defined for this specific vid:pid.
The missing TTYs are not a real issue though, if the modem has a QMI
port, the QMI port should be responsive.

-- 
Aleksander