MC7455 modem stops responding over QMI and serial
alexb at meshplusplus.com
Wed Jul 29 20:50:34 UTC 2020
I have a few MC4755 modems connected using the qmi_wwan driver (on linux
4.14.171) managed by modemmanager. After some time a few of these modems
have completely stopped responding to any commands over QMI, not showing
up in modemmanager. The AT command serial port (/dev/ttyUSB2) and the
NMEA serial port (/dev/ttyUSB1) are both missing. The only port that is
available is /dev/ttyUSB0, which seems to be for diagnostic monitoring.
Nothing is sent over this port, however.
This issue persists after a cold reboot. The qmi_wwan driver doesn’t
show anything strange in dmesg log. What could be causing this issue?
Thanks in advance.
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