Unable to connect using a Quectel EC25-E modem and libqmi 1.18.0

[xyj]

> That is rather unexpected.  There aren't really any differences between
> v4.9, v4.10 or v4.11 which should make them behave differently.  Unless
> we consider stable updates.  Could this be another fallout of the bug
> introduced by commit 833415a3e781 ("cdc-wdm: fix "out-of-sync" due to
> missing notifications")?  If so, then the fix (revert) for this bug is
> backported to v4.11.2, v4.10.17 and v4.9.29.

Base on v4.9.28, I try to compile cdc-wdm.ko based on your last commit 833415a3e781.
It seems work but some work should be prepared. After many tests, the following processes should work:

1. echo Y > /sys/class/net/wwan0/qmi/raw_ip

2. ifconfig wwan0 up

3. qmicli -p -d /dev/cdc-wdm0 --device-open-net="net-raw-ip|net-no-qos-header" --wds-start-network= --client-no-release-cid

4. udhcpc -i wwan0


> Did you try configuring the address and routing manually?  If using
> raw-ip: Are you sure the DHCP client supports it?  I know the Busybox
> DHCP client works and the ISC DHCP client fails.  Unsure about the
> others.  You appear to use Roy Marple's client?  I don't remember if I
> tested that one with raw-ip.

I use udhcpc (not busybox) package (apt install udhcpc) to obtain IP successfully.
Of course I tried `busybox udhcpc` and failed to obtain IP.

------------

Although IP obtained successfully, the information from `ip a` is quirk, for example:

1: lo

......
  
3. wwan0: <....>
	link/none					--> this line is quirk.
	inet 10.49.172.92/29 scope global wwan0
	....

Is it because of raw-ip mode? More knowledge to learn.

Jimmy Xu