How force EC21 with ModemManager to use cdc primary port

Technical Subjects Driver
#1

We are trying to setup our EC21 Modem with the ModemManager 1.10.8 (open embedded zeus) and with the kernel 5.4. Randomly it takes the correct primary port, but 1 of 10 times.

defconfig is cofigured like the pdf description says and wwan0 is available and also /cdc-wdm0 is there. With ModemManager —debug it says qmi not availabel after a reset.

The file qmi_wwan_q.c/o isnt installed.

How can I fix this issue?
Which logs would help for debug?

BR
Cris

#2

If you would like to use ModemManager to set up datacall, please use the original qmi_wwan.c in the kernel source.

#3

jouralctl -xu ModemManager > log.txt

#4

Hi Bean Wang

Thank you very much for your response.

I tried to reply you over the platform, but it tells me, that new users are not allowed to upload files.

So I wrote you on forums@quectel.com.

In this logs.zip you will find four logfiles:

  • journalctl -xu ModemManager > log.txt

  • journalctl > kernel_log.txt

  • sudo /usr/sbin/ModemManager --debug --log-file ./ModemManager_debug_log.txt

  • Same but with a hard reset of the modem (power off / power on)

  • sudo /usr/sbin/ModemManager --debug --log-file ./ModemManager_debug_after_modem_reset_log.txt

Do you see anything, where indicate the issue? What I see, it is communicating over /dev/cdc-wdm0 but “finishes with QMI port open operation finished”.

Thanks in advance.

BR

Cris

#5

Please show the result:

cat /sys/kernel/debug/usb/devices

systemctl status ModemManager

and send the ModemManager log to bean.wang@quectel.com.

If possible, please try the lastest version of ModemManager such as 1.18.x.

I’ve tried it.

#6

I’ve found the issue.

With yocto openembedded, the “packagegroup-base” has a RDEPEND for “ofono”.

When you analise on the target who wants to acces the “cdc-wdm0” device with “lsof”, you see dbus and “ofono”. This is the reason for the broken pipes with the modemmanager.

For all yocto developers around there.
Write a packagegroup-base.bbappend with this content:
RDEPENDS_packagegroup-base-3g_remove = "
ofono"

Good luck!

Cheers
Cris

#7

Good to hear that.

You can use the tool fuser and lsof to find it out.