I have a Thinkpad T550 and initially had a similar issue:
With the stock kernel in Sid:
dmesg |grep psmouse
psmouse serio1: synaptics: The touchpad can support a better bus than
the too old PS/2 protocol. Make sure MOUSE_PS2_SYNAPTICS_SMBUS and
RMI4_SMB are enabled to get a better touchpad experience.
psmouse serio1: synaptics: Touchpad model: 1, fw: 8.1, id: 0x1e2b1,
caps: 0xf003a3/0x943300/0x12e800/0x10000, board id: 3053, fw id: 2560
psmouse serio1: synaptics: serio: Synaptics pass-through port at
isa0060/serio1/input0
psmouse serio2: trackpoint: IBM TrackPoint firmware: 0x0e, buttons: 3/3
I built a new kernel 'the Debian way' and now everything looks good:
egrep 'MOUSE_PS2_SYNAPTICS_SMBUS|RMI4_SMB' /boot/config-4.19.16
CONFIG_MOUSE_PS2_SYNAPTICS_SMBUS=y
CONFIG_RMI4_SMB=y
dmesg |grep psmouse
[ 2.185730] psmouse serio1: synaptics: queried max coordinates: x
[..5676], y [..4758]
[ 2.213569] psmouse serio1: synaptics: queried min coordinates: x
[1266..], y [1096..]
[ 2.213572] psmouse serio1: synaptics: Trying to set up SMBus access
[ 2.717537] psmouse serio2: trackpoint: IBM TrackPoint firmware:
0x0e, buttons: 3/3
egrep -i "synap|alps|etps|elan" /proc/bus/input/devices
N: Name="Synaptics TM3053-003"
sudo dmesg | grep -i len00
[ 0.343154] pnp 00:03: Plug and Play ACPI device, IDs LEN0071 PNP0303
(active)
[ 0.343168] pnp 00:04: Plug and Play ACPI device, IDs LEN002c PNP0f13
(active)
sudo dmesg | egrep -i "touch|mouse|track"
[ 1.114322] mousedev: PS/2 mouse device common for all mice
[ 2.185730] psmouse serio1: synaptics: queried max coordinates: x
[..5676], y [..4758]
[ 2.213569] psmouse serio1: synaptics: queried min coordinates: x
[1266..], y [1096..]
[ 2.213572] psmouse serio1: synaptics: Trying to set up SMBus access
[ 2.717537] psmouse serio2: trackpoint: IBM TrackPoint firmware:
0x0e, buttons: 3/3
[ 2.790142] input: TPPS/2 IBM TrackPoint as
/devices/rmi4-00/rmi4-00.fn03/serio2/input/input9
That said, I don't really notice any different behavior with the
touchpad :-)
The touchpad and the trackpoint still work but I haven't figured out how
to enable edge scrolling, circular scrolling, nor to set features like
sensitivity.
Someone above stated that he installed xserver-xorg-input-synaptics.
That package has been depcrecated by xserver-xorg-input-libinput:
apt-cache show xserver-xorg-input-libinput
...
This package provides the driver for input devices using libinput library.
It can handle keyboards, mice and touchpads, and essentially replaces the
separate -evdev and -synaptics drivers.
