lenovo-ymc: SW_TABLET_MODE switch registered but no events emitted on ThinkBook 14 2-in-1 G6 IPL (type 22AR)

[Pedro Miguel Vieira]

Summary
  -------
  On a Lenovo ThinkBook 14 2-in-1 G6 IPL, the lenovo-ymc driver binds
and
  registers an input switch "Lenovo Yoga Tablet Mode Control switch"
that
  advertises SW_TABLET_MODE, but physically folding the device into
tablet mode
  (and back) produces no SW_TABLET_MODE events. As a result GNOME never
  auto-disables the internal keyboard/touchpad in tablet mode, causing
ghost
  key presses and cursor jumps while held as a tablet.
  
  Hardware
  --------
  Vendor/Model : LENOVO ThinkBook 14 2-in-1 G6 IPL
  DMI product  : 22AR
  Board        : LNVNB161216
  BIOS         : U1CN09WW (2026-05-12)
  Chassis type : 31 (convertible)
  
  Software
  --------
  Distro  : Fedora 44
  Kernel  : 7.2.11-200.fc44.x86_64 (also present/affected: 7.2.12-
200.fc44)
  Desktop : GNOME Shell 50.6, Wayland
  
  Driver
  ------
  Module    : lenovo-ymc (drivers/platform/x86/lenovo/lenovo-ymc.ko)
  WMI GUID  : 06129D99-6083-4164-81AD-F092F9D773A6
  Maintainer: Gergo Koteles <soyer@xxxxxx>
  
  Evidence
  --------
  1) Switch registers the SW_TABLET_MODE capability:
     /sys/class/input/input44/capabilities/sw = 0x2  (SW_TABLET_MODE
bit set)
  
  2) evtest shows the capability but NO events when folding to/from
tablet mode
     (folded the hinge several times; "Testing ..." stayed empty until
Ctrl+C):
  
     $ sudo evtest /dev/input/event18
     Input device name: "Lenovo Yoga Tablet Mode Control switch"
     Supported events:
       Event type 0 (EV_SYN)
       Event type 5 (EV_SW)
         Event code 1 (SW_TABLET_MODE) state 0
     Testing ... (interrupt to exit)
     ^C
     (no SW_TABLET_MODE events emitted while folding)
  
  3) dmesg shows lenovo-ymc binding cleanly (no errors), creating the
device via
     WMI GUID 06129D99-6083-4164-81AD-F092F9D773A6.
  
  Expected: folding emits SW_TABLET_MODE=1, unfolding emits
SW_TABLET_MODE=0;
            GNOME then auto-inhibits the internal keyboard/touchpad.
  Actual:   no events ever emitted; switch stuck at state 0 regardless
of hinge
            position; internal keyboard/touchpad stay active in tablet
mode.
  
  Note: the machine is a convertible (chassis type 31), so it passes
the
  "only bind on convertible DMI chassis-type" check; binding is not the
problem.
  The YMC WMI query/notification path does not report tablet-mode state
changes
  on this model. Likely needs model/variant support (or a YMC WMI
method/quirk)
  for the ThinkBook 14 2-in-1 G6 IPL (type 22AR, board LNVNB161216).
  
  Happy to test patches and provide an acpidump / WMI method dumps on
request;
  this is my daily-driver machine.