I own a Yoga 7 2-in-1 14AHP9 and the latest linux kernel breaks pen input. Now the pen is always recognized as the “eraser”. After installing and booting the lts kernel the problem goes away.
I’m posting here so others with the same issue find the solution quicker.
Should I report this issue somewhere?
To test I was using libinput debug-tablet where I get Tool: eraser serial 0x80e51447, id 0x219 when I should be getting Tool: pen serial 0x80e51447, id 0x219.
Also evtest /dev/input/event6 to monitor evdev, where it reports type 1 (EV_KEY), code 321 (BTN_TOOL_RUBBER), value 0 instead of type 1 (EV_KEY), code 320 (BTN_TOOL_PEN), value 0.