I'm trying to record the dpi for my touchpad since it seems quite slow. However it can't seem to compute any distance as I move my finger. This is the output from mouse-dpi-tool. It seems to record the frequency fine, but doesn't read any distance:

sudo ./mouse-dpi-tool /dev/input/event7
Mouse FocalTechPS/2 FocalTech Touchpad on /dev/input/event7
Move the device 250mm/10in or more along the x-axis.
Pause 3 seconds before movement to reset, Ctrl+C to exit.
Covered distance in device units:        0 at frequency 70.4Hz 	/^C
Estimated sampling frequency: 70Hz (mean 62Hz)
To calculate resolution, measure physical distance covered
and look up the matching resolution in the table below
       0mm	    0.00in	     400dpi
       0mm	    0.00in	     600dpi
       0mm	    0.00in	     800dpi
       0mm	    0.00in	    1000dpi
       0mm	    0.00in	    1200dpi
       0mm	    0.00in	    1400dpi
       0mm	    0.00in	    1600dpi
       0mm	    0.00in	    1800dpi
       0mm	    0.00in	    2000dpi
       0mm	    0.00in	    2200dpi
       0mm	    0.00in	    2400dpi
If your resolution is not in the list, calculate it with:
	resolution=0/inches, or
	resolution=0 * 25.4/mm

Output from udevadm info:

P: /devices/platform/i8042/serio4/input/input12/event7
N: input/event7
E: DEVNAME=/dev/input/event7
E: DEVPATH=/devices/platform/i8042/serio4/input/input12/event7
E: ID_BUS=i8042
E: ID_INPUT=1
E: ID_INPUT_TOUCHPAD=1
E: ID_INPUT_TOUCHPAD_INTEGRATION=internal
E: LIBINPUT_DEVICE_GROUP=11/2/12/0:isa0060/serio4
E: MAJOR=13
E: MINOR=71
E: SUBSYSTEM=input
E: USEC_INITIALIZED=2131871
Entry for hwdb match (replace XXX with the resolution in DPI):
mouse:unknown bus type:v0002p0012:name:FocalTechPS/2 FocalTech Touchpad:
 MOUSE_DPI=XXX@70

This is a FocalTech Touchpad on an Asus UX303UB latpop.