Fibocom L850-GL hangs upon connect.

[Aleksander Morgado]

Hey,

> However, once ttyACM0 gets tied up and times out after 10 command retries,
> ModemManager removes the modem:
> ModemManager[13213]: <error> [1533754896.224557] (tty/ttyACM0) at port timed
> out 10 consecutive times, marking modem
> '/org/freedesktop/ModemManager1/Modem/0' as invalid
> ModemManager[13213]: <debug> [1533754896.224790] Removing from DBus bearer
> at '/org/freedesktop/ModemManager1/Bearer/0'
> ModemManager[13213]: <debug> [1533754896.224833] [device
> /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5] unexported modem from
> path '/org/freedesktop/ModemManager1/Modem/0'
> ModemManager[13213]: <debug> [1533754896.224854] Periodic signal checks
> disabled
> ModemManager[13213]: <debug> [1533754896.225124] (ttyACM0) device open count
> is 0 (close)
> ModemManager[13213]: <debug> [1533754896.225150] (ttyACM0) closing serial
> port...
> ModemManager[13213]: <debug> [1533754896.279512] (ttyACM0) serial port
> closed
> ModemManager[13213]: <debug> [1533754896.279592] (ttyACM0) forced to close
> port
> ModemManager[13213]: <debug> [1533754896.279621] (ttyACM2) device open count
> is 0 (close)
> ModemManager[13213]: <debug> [1533754896.279637] (ttyACM2) closing serial
> port...
> ModemManager[13213]: <debug> [1533754896.279670] (ttyACM2) serial port
> closed
> ModemManager[13213]: <debug> [1533754896.279697] (ttyACM2) forced to close
> port
> ModemManager[13213]: <debug> [1533754896.279718] Modem (Generic)
> '/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5' completely disposed
>
> This whole time, I'm able to connect to ttyACM2 with minicom and issue AT
> commands and get replies. ModemManager is only treating ACM0 as the modem
> and doesnt care about ACM2 (even though it will identify it as an AT command
> port)
> I've attached a complete boot log showing the process with both ModemManager
> and NetworkManager in debug mode:
> https://gist.github.com/danielewood/8e19a0832266638c4da2f163ac3520a8
>

Hum... looks like the ttyACM0 port disconnection didn't succeed, so it
stays in connected mode and MM ends up saying the port is unusable and
flag the modem as invalid. Is this clearly always reproducible?

>
> If this modem is going to end up stuck with pure PPP and therefore maxing
> out at 25Mbps, then I'm not too concerned anyways since its use is rather
> limited. I just wish I could figure out how to switch this thing to MBIM
> (Tried everything listed in the AT Command reference guide, including
> factory resets and defaults.).
>

Talked to Fibocom engineers and unfortunately that firmware version
you're using cannot do MBIM :/


-- 
Aleksander
https://aleksander.es