Problem doing 'echo Y > /sys/class/net/ww*/qmi/raw_ip'

[Martin Schmid]

Hello everybody

Maybe someone has an idea for this:

I'm using Debian installations, all with sysvinit so far. There are some 
systemd components present since debian Jessie.
I've testet with multiple kernel and libqmi versions. The current setup 
is a Buster with kernel 4.19.37 and qmicli 1.22.0.
The modem is a SIM7500 or SIM7600, both needing raw_ip.

I can control the modem and it's looking good so far, except that 
qmi-network is unable to set raw_ip to 'Y'.

The file /sys/class/net/ww*/qmi/raw_ip' exists and is readable. But when 
trying to alter its content, there's an error: 'device or resource busy'

I could't find out why the device should be busy and what process is 
keeping it unconfigurable.

All ifdown, 'ip link set down' does not help. Even removing qmi_wwan and 
readding it does not work.

Looking at /proc/net/netlink doesn't tell me anything. At the moment, I 
cannot match the eth id to an interface name.

Is there a solution for this or are there debugging hints?

Regards,

martin

-- 
Martin Schmid
APS systems AG, Neumatt 4, CH-4626 Niederbuchsiten
Tel direkt: +41 62 389 8891, Tel: +41 62 517 8833
www.aps-systems.ch