On my alps glidepoint touchpad device that appears to be synaptics
driver, the pointer is far too fast to be usable by default. If I use
synclient to drop MaxSpeed, MinSpeed and AccelFactor drastically, it
is still too fast but vaguely usable. There appears to be a minimum
speed. Upstream bug is probably this one, that has been neglected for
only 6 years now:
https://bugs.freedesktop.org/show_bug.cgi?id=38998
This is what's detected by Xorg at startup:
[ 20.108] (II) Using input driver 'synaptics' for 'AlpsPS/2 ALPS GlidePoint'
[ 20.108] (**) AlpsPS/2 ALPS GlidePoint: always reports core events
[ 20.108] (**) Option "Device" "/dev/input/event1"
[ 20.148] (--) synaptics: AlpsPS/2 ALPS GlidePoint: x-axis range 0 - 2944 (res 31)
[ 20.148] (--) synaptics: AlpsPS/2 ALPS GlidePoint: y-axis range 0 - 1536 (res 31)
[ 20.148] (--) synaptics: AlpsPS/2 ALPS GlidePoint: pressure range 0 - 127
[ 20.148] (II) synaptics: AlpsPS/2 ALPS GlidePoint: device does not report finger width.
[ 20.148] (--) synaptics: AlpsPS/2 ALPS GlidePoint: buttons: left right middle double triple
[ 20.148] (--) synaptics: AlpsPS/2 ALPS GlidePoint: Vendor 0x2 Product 0x8
[ 20.148] (--) synaptics: AlpsPS/2 ALPS GlidePoint: invalid finger width range. defaulting to 0 - 15
[ 20.148] (--) synaptics: AlpsPS/2 ALPS GlidePoint: touchpad found
[ 20.148] (**) AlpsPS/2 ALPS GlidePoint: always reports core events
[ 20.200] (**) Option "config_info" "udev:/sys/devices/platform/i8042/serio1/input/input2/event1"
[ 20.200] (II) XINPUT: Adding extended input device "AlpsPS/2 ALPS GlidePoint" (type: TOUCHPAD, id 15)
[ 20.200] (**) synaptics: AlpsPS/2 ALPS GlidePoint: (accel) MinSpeed is now constant deceleration 2.5
[ 20.200] (**) synaptics: AlpsPS/2 ALPS GlidePoint: (accel) MaxSpeed is now 1.75
[ 20.200] (**) synaptics: AlpsPS/2 ALPS GlidePoint: (accel) AccelFactor is now 0.060
[ 20.200] (**) AlpsPS/2 ALPS GlidePoint: (accel) keeping acceleration scheme 1
[ 20.200] (**) AlpsPS/2 ALPS GlidePoint: (accel) acceleration profile 1
[ 20.200] (**) AlpsPS/2 ALPS GlidePoint: (accel) acceleration factor: 2.000
[ 20.200] (**) AlpsPS/2 ALPS GlidePoint: (accel) acceleration threshold: 4
[ 20.201] (--) synaptics: AlpsPS/2 ALPS GlidePoint: touchpad found
[ 20.201] (II) config/udev: Adding input device AlpsPS/2 ALPS GlidePoint (/dev/input/mouse0)
It becomes vaguely usable somewhere along the way to:
MinSpeed=0.00001
MaxSpeed=0.00175
AccelFactor=0.00001241
but maxes out in usability way before those tiny numbers.