RM500U-EA under linux: NETDEV WATCHDOG: wwan0 (cdc_mbim): transmit queue 0 timed out


I’m using your new module RM500U-EA under linux embedded arm 64 based with kernel 5.15. I’m currently running RM500UEAAAR03A03M2G_01.001.01.001 firmware with the modem and configuring the MBIM mode:


I can connect to the internet via mbimcli commands, but when I try a speed test the following error occurs:

NETDEV WATCHDOG: wwan0 (cdc_mbim): transmit queue 0 timed out

I have no problems mantaining the connectivity without a full bandwidth test.

After that the modem becomes unresponsive. I have no problems instead using the modem in NCM mode.

Any idea? Is there a firmware update available that fixes the issue?

Thank you in advance!


Hi again, I’ve found this post written by one of the major contributor to ModemManager:


This is very likely the modem firmware getting stuck forever. While
the “transmit queue 0 timed out” is a legit message that may in theory
happen without bad effects; in my experience this happens whenever the
device goes silent due to a firmware bug that leaves the device stuck.
I have personally never seen this message associated with any other
case than device firmware problems. If the device is good enough, it
may have its own way to detect the problem and reboot itself,
otherwise it will just get stuck until you power cycle it.

Maybe the RM500U-EA MBIM interface is not yet fully functional?

Thank you in advance