Random QMI port probe failures after ed13e053cd42 ("port-probe: fix custom init probing not having open AT port")

[Dan Williams]

Excellent. Thanks for following up!

Dan
On Mar 10, 2025 at 7:16 AM -0500, Lech Perczak <lech.perczak at camlingroup.com>, wrote:
> Hello Aleksander, Dan
>
> It works perfect now again, thanks!
> I'm sorry that I totally forgot about this thread - but still letting you know.
> With kind regards,
> Lech
> W dniu 22.12.2024 o 19:13, Aleksander Morgado pisze:
> > Hey,
> >
> > On Sun, Dec 22, 2024 at 6:49 PM Aleksander Morgado <aleksander.morgado at gmail.com> wrote:
> > >
> > >
> > > > On Sun, Dec 22, 2024 at 6:37 PM Aleksander Morgado <aleksander.morgado at gmail.com> wrote:
> > > > > Hey,
> > > > > >
> > > > > > > > > After updating to the latest main (at eda130f3bf1c), in our team
> > > > > > > > > we've noticed, that in our CI, that QMI port sometimes fails to
> > > > > > > > > probe,
> > > > > > > > > with Telit LE910C4-WWXD. The result is the modem having only AT
> > > > > > > > > ports
> > > > > > > > > available, thus falling back to using PPP for the data connection.
> > > > > > > >
> > > > > > > > Well that's not awesome; I'll dig into it. If you figure out anything
> > > > > > > > too, let me know.
> > > > > > > >
> > > > > > >
> > > > > > > When this happens, does MM attempt to probe the port as AT before
> > > > > > > trying QMI?
> > > > > > >
> > > > > >
> > > > > > With the changes in that referenced commit, it looks like serial_probe_step() may be running serial_open_at() also for the QMI and MBIM ports, which is not right, as that would create a new MMSerialPort in ctx->serial.
> > > > > >
> > > > > > The serial_probe_step() (ideally renamed as probe_step() to make it clearer that it is not serial-specific) should not run any serial-specific operation (e.g. CUSTOM_INIT, AT_OPEN_PORT, ....) for ports that do not require any AT or QCDM probing.
> > > > > >
> > > > > > WDYT?
> > > >
> > > > The issue can be reproduced with modems for which the corresponding plugin has "custom_init" configured, e.g. Telit or Cinterion:
> > > >
> > > > ModemManager[4112]: <dbg> [1734889629.161510] [cdc-wdm0/probe] no AT/QCDM/QMI probing in possible MBIM port
> > > > ModemManager[4112]: <dbg> [1734889629.162057] [cdc-wdm0/probe] port is not AT-capable
> > > > ModemManager[4112]: <dbg> [1734889629.162867] [cdc-wdm0/probe] port is not QCDM-capable
> > > > ModemManager[4112]: <dbg> [1734889629.163621] [cdc-wdm0/probe] port is not QMI-capable
> > > > ModemManager[4112]: <dbg> [1734889629.164981] [cdc-wdm0/probe] launching port probing: 'mbim'
> > > > ModemManager[4112]: <msg> [1734889629.166516] [cdc-wdm0/probe] probe step: start
> > > > ModemManager[4112]: <msg> [1734889629.166988] [cdc-wdm0/probe] probe step: custom init open port
> >
> > I tried to fix this with https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/merge_requests/1273
> >
> > Let us know if this solves the problem completely or not.
> > ___
> > This email originated from outside of Camlin Group. Do not click on links or open attachments unless you are confident they are secure. If in doubt, please raise a security incident via the following portal: Camlin Helpdesk – Report an Information Security Incident/Non-Conformance
> --
> Pozdrawiam/With kind regards,
> Lech Perczak
>
> Sr. Software Engineer
> Camlin Technologies Poland Limited Sp. z o.o.
> Strzegomska 54,
> 53-611 Wroclaw
> Tel:     (+48) 71 75 000 16
> Email:   lech.perczak at camlingroup.com
> Website: http://www.camlingroup.com
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