Created attachment 258415 [details] dmesg output: boot with keyboard attached, detached and reattached. On the thinkpad helix with the ultrabook pro keyboard dock the trackpoint and the trackpad do not work after the tablet is detached and then reattached. With Kernel 4.11.7 trackpoint and touch work as expected when reattaching the keyboard dock. The problem first occurred after around 4.12.5. Both trackpoint and trackpad work when the device is booted with the keyboard attached. Both also work when the device is booted without the keyboard attached, and then the keyboard is attached for the first time. After subsequent detach-reattach the trackpoint and touchpad no longer work. In all cases keyboard input still works. Attaching a usb mouse works. As does a usb thinkpad compact keyboard (which has a trackpoint). The problem does not appear to be driver related as this problem occurs both when the libinput driver takes care of the touchpad and trackpoint, and when the synaptics driver drives the touchpad and evdev the trackpoint. I've attached dmesg output from boot with keyboard attached, detached then reattached. Also dmesg output from boot without the keyboard attached and attached for the first time.
Created attachment 258417 [details] dmesg output: boot without keyboard attached, then attached for first time
Created attachment 258419 [details] Xorg log: detach, reattach keyboard dock, then attached usb thinkpad compact keyboard
Possibly related to bug https://bugzilla.kernel.org/show_bug.cgi?id=195707