On 02.05.22 21:32, Alan Stern wrote: Hi, I am happy to help, if I can. > The usbmon trace shows that quite a lot happens during re-enumeration > that doesn't happen during the reset-resume. No doubt the reason for > this is that the cdc-wdm driver doesn't have a real reset-resume > handler; the operations it carries out for a reset-resume are the same > as for a normal resume, and that clearly is not appropriate here. Doing reset_resume() for WDM is problematic. The whole point of WDM as a protocol is to put the configuration of a device into user space. What is a kernel driver to do in that case.? > For example, the usbmon trace shows that the kernel sends a > Set-Interface request to the modem during re-enumeration and then does a > whole lot of probing that I don't understand. None of this stuff > happens during the reset-resume. Probably the modem decides that > without any of this extra configuration, it doesn't need to do > anything -- and that's why it disconnects itself. > Are you sure that stuff comes from CDC-WDM in the case of reenumeration? WDM does not do set_interface() in any case. Regards Oliver
