Modem kernel driver changes from cdc_mbim to qmi_wwan after suspend/resume?

[Bjørn Mork]

Aleksander Morgado <aleksander at aleksander.es> writes:

> The user reports the following:
>
> root at angelo-thinkpad-x1-carbon-4th:~# cat /sys/bus/usb/drivers/qmi_wwan/new_id
> 1199 9079
> root at angelo-thinkpad-x1-carbon-4th:~# cat
> /sys/bus/usb/drivers/qmi_wwan/remove_id
> 1199 9079
>
> Does this mean something is injecting those ids dynamically during runtime?

Yes.  And that's the problem.  It makes qmi_wwan attempt to bind to any
USB interface on this device, racing with the drivers that should do so.

Using "new_id" from scripts is almost always a bug.  At least for
complex composite device with multiple compositions like the EM7455. You
can make it work, but those who are able to do that will probably find
it easier to patch and build a new kernel...

"new_id" is primarily a debugging and development knob.



Bjørn