I'm hitting this exact same issue with a different device, it's a development board that communicates over USB CDC (an Adafruit Bluefruit Micro, a little bluetooth LE microcontroller board). The device has similar behavior as the mentioned MediaTek preloader where it implements a very basic USB CDC endpoint and can abruptly disconnect at times if for example it times out waiting for a response from the host computer.
Not sure what else I can add unfortunately to the discussion but your debugging info is super helpful to confirm this appears to be the same issue. I'm not familiar with ModemManager either but is there any way to rollback to an older version and pinpoint what change caused the issue? -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1473246 Title: MediaTek Preloader on a mobile device triggers cdc_acm kernel module usage by ModemManager To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/modemmanager/+bug/1473246/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
