EM9291 Soft Reboot Issue

1

Hi Sierra team,

I am using the EM9291 modem on a Linux host. I observe the following issue:

After performing a soft reboot of the Linux kernel, the modem does not reconnect to the 5G core automatically.
The modem appears inactive, and network attachment fails.
The only way to recover connectivity is to manually reset the modem:
mmcli -m 0 --reset

After the reset, the modem successfully connects to the 5G core.
Environment Details:
Modem: EM9291
Linux Kernel: 6.6.36
ModemManager version: mmcli 1.22.0
Interface: Using techship USB module

Is there a recommended way, patch, or firmware update to handle automatic reattach after a Linux soft reboot?
Has anyone experienced similar behavior with the EM9291 and Linux kernel?

Thanks,
Arti

2

How about setting to 5g only in at!selrat?

How about resetting telecom stack by at+cfun=0 and at+cfun=1 ?

3

Resetting using AT command and mmcli command works fine.
but when we reboot the kernel (6.6.36), we are facing issues.

After reboot we have to reset the EM9291 modem again to get it working

4

When issue happens, what is the return of the following?


at!entercnd="A710"
AT+Cfun?
AT!pcinfo?
AT!CUSTOM?
5

+CFUN: 1

OK

State: Online
LPM voters - Temp:0, Volt:0, User:0, W_DISABLE:0, IMSWITCH:0, BIOS:0, LWM2M:0, OMADM:0, FOTA:0, NVCRIT:0, RFCAL:0, MMWCAL:0, RFC_INIT:0
LPM persistence - None

OK

!CUSTOM:
GPSENABLE 0x01
GPSSEL 0x01
IMCONFIG 0x02
IPV6ENABLE 0x01
SIMLPM 0x01
USBSERIALENABLE 0x01
ICMPINTSRVDIS 0x01

OK

6

i can see it is ONLINE mode now.