Touchpad backlash

Question

I am running Ubuntu 13.04 on a Dell Inspiron 17R SE. It has an ALPS touchpad.

The problem is that this touchpad has backlash. By this I mean that if I move the cursor in one direction and then reverse it, I will have to move my finger a short distance before it starts moving again. I have also noticed this behavior on a Fujitsu Lifebook with Ubuntu 13.10.

The experience is very similar to the mechanical phenomenon that is nicely explained in this Wikipedia article.

Has anyone else experienced this? Is it a flaw in the hardware or something that could be debugged and corrected in software?

Answer 1

Finally, I have a solution. I bought an XPS 13 with Ubuntu preinstalled and was surprised to find the same issue, although much less severe, with this laptop.

The setting is called "Hysteresis" in synclient, a name that does seem related.

kalle@Kalle-XPS:~$ synclient
Parameter settings:
HorizHysteresis         = 1000
VertHysteresis          = 1000

With xinput, the name is the somewhat less obvious "Synaptics noise cancellation":

kalle@Kalle-XPS:~$ xinput --list-props 11
Device 'DLL075B:01 06CB:76AF Touchpad':
Synaptics Noise Cancellation (302): 0, 0

As you can see above, I've set this parameter to zero instead of the default value of 6. The touchpad is really smooth now.

The exact procedure for finding out the ID of the touchpad and setting parameters is explained on the community wiki: https://help.ubuntu.com/community/SynapticsTouchpad

In my case, the ID of the touchpad was 15 and the following command did it:

xinput --set-prop 11 302 0 0