Modem Reboot -> ModemManager Restart

[Jack Broderick]

Hello,

I have found a very strange issue using an EM7455 with:

MM: 1.16.2
libqmi: 1.28.2
OpenWRT: 19.02, kernel 4.14.215

I have been running a "soak" test to debug another long term connectivity
issue I have been debugging. The unit was connected to my test LTE network
for approximately 6 days according to the bearer duration.

Eventually the interface goes down with the following:
Sep  8 16:11:31 E1500 ModemManager[4765]: <info>  [modem5/bearer2850]
bearer call end reason (1): 'generic-unspecified'
Sep  8 16:11:31 E1500 ModemManager[4765]: <info>  [modem5/bearer2850]
bearer verbose call end reason (2,219): [internal] lpm-or-power-down
Sep  8 16:11:31 E1500 ModemManager[4765]: <info>  [modem5] state changed
(connected -> registered)
Sep  8 16:11:31 E1500 ModemManager[4765]: <info>  [modem5/bearer2850]
connection #1 finished: duration 523672s, tx: 0 bytes, rx :0 bytes
Sep  8 16:11:32 E1500 ModemManager[4765]: <warn>  [modem5] couldn't load
operator code: Current operator MCC/MNC is still unknown
Sep  8 16:11:32 E1500 ModemManager[4765]: <warn>  [modem5] couldn't load
operator name: Current operator description is still unknown

I am not sure what the "lpm-or-power-down" is exactly. Perhaps it is an
internal modem sleep/reboot after a certain amount of time of inactivity.
This could make sense after 6 days of connectivity. The issue is, however,
that when the interface attempts to reconnect, there is an issue with
ModemManager:

Sep  8 16:11:43 E1500 netifd: wan_b (9524): error: couldn't create manager:
GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface
?org.freedesktop.DBus.ObjectManager? on object at path
/org/freedesktop/ModemManager1

it eventually restarts the service:
Sep  8 16:11:44 E1500 ModemManager[4765]: <info>  ModemManager is shut down

and my modem reboots (times in UTC):
Sep  8 16:12:22 E1500 kernel: [1300867.611138] usb 1-1.2: USB disconnect,
device number 8
Sep  8 16:12:22 E1500 kernel: [1300867.616939] qcserial ttyUSB0: Qualcomm
USB modem converter now disconnected from ttyUSB0
Sep  8 16:12:22 E1500 kernel: [1300867.625373] qcserial 1-1.2:1.0: device
disconnected
Sep  8 16:12:22 E1500 kernel: [1300867.631010] qcserial ttyUSB1: Qualcomm
USB modem converter now disconnected from ttyUSB1
Sep  8 16:12:22 E1500 kernel: [1300867.639441] qcserial 1-1.2:1.2: device
disconnected
Sep  8 16:12:22 E1500 kernel: [1300867.645046] qcserial ttyUSB2: Qualcomm
USB modem converter now disconnected from ttyUSB2
Sep  8 16:12:22 E1500 kernel: [1300867.653463] qcserial 1-1.2:1.3: device
disconnected
Sep  8 16:12:22 E1500 kernel: [1300867.658919] qmi_wwan 1-1.2:1.8 wwan0:
unregister 'qmi_wwan' usb-ci_hdrc.1-1.2, WWAN/QMI device
Sep  8 16:12:22 E1500 kernel: [1300867.720213] qmi_wwan 1-1.2:1.10 wwan1:
unregister 'qmi_wwan' usb-ci_hdrc.1-1.2, WWAN/QMI device

I have determined based on the AT!GSTATUS taken at roughly 9/15/2021 17:36
ET

aat!gstatus?
!GSTATUS:
Current Time:  624031           Temperature: 67

The uptime in seconds corresponds to 7 days, 5 hours, 20 minutes so it
seems the modem did fully reboot at roughly the time of the kernel logs.

I checked the crash dump of the modem:
at!gcdump
No crash data available

And it appears the reboot was not because of a crash...

I unfortunately did not have ModemManager in debug mode, but I'm curious of
two things:

1. If anyone has seen that disconnect reason in a modem before
2. What could cause ModemManager to restart it's process as a result of a
modem rebooting?

I know that was very long winded but I'd appreciate any feedback.

Thanks!
Jack





-- 
Jack Broderick
R&D Engineer
Council Rock
(585)505-5959
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/modemmanager-devel/attachments/20210915/6a480e56/attachment.htm>