T420 touchpad udevadm info.

P: /devices/platform/i8042/serio1/input/input8/event8
N: input/event8
S: input/by-path/platform-i8042-serio-1-event-mouse
E: DEVLINKS=/dev/input/by-path/platform-i8042-serio-1-event-mouse
E: DEVNAME=/dev/input/event8
E: DEVPATH=/devices/platform/i8042/serio1/input/input8/event8
E: ID_BUS=i8042
E: ID_INPUT=1
E: ID_INPUT_HEIGHT_MM=36
E: ID_INPUT_TOUCHPAD=1
E: ID_INPUT_TOUCHPAD_INTEGRATION=internal
E: ID_INPUT_WIDTH_MM=66
E: ID_PATH=platform-i8042-serio-1
E: ID_PATH_TAG=platform-i8042-serio-1
E: ID_SERIAL=noserial
E: LIBINPUT_DEVICE_GROUP=11/2/7:isa0060/serio1
E: LIBINPUT_MODEL_JUMPING_SEMI_MT=1
E: LIBINPUT_MODEL_SYNAPTICS_SERIAL_TOUCHPAD=1
E: MAJOR=13
E: MINOR=72
E: SUBSYSTEM=input
E: USEC_INITIALIZED=8951445