Monday, 16 April 2012

AlpsPS/2 ALPS DualPoint TouchPad on Arch linux

In my new Dell Latitude, there is an AlpsPS/2 ALPS DualPoint touchpad. When I installed Arch linux on it the touchpad worked fine for me. I do not use the touchpad button and prefer to tap on the touchpad for a click. This feature worked fine with the initial configuration. However, after a system update which included a kernel update too, tap did not work.

I had not gotten into details of the touchpad before this incident. When I found it was not a Synaptics touchpad, I got scared that I might not get a decent linux driver for it. Just about a month ago I was looking for a decent driver that supports Nvidia Optimus tecnology; but all my efforts were in vain.

As I started looking for a driver for my touchpad, I found out that the synaptics driver is not only for synaptics touchpads. So, I installed xf86-input-synaptics package. Tap for click started working as the default /etc/X11/xorg.conf.d/10-synaptics.conf has the configuration for tap.

        Option "TapButton1" "1"
        Option "TapButton2" "2"
        Option "TapButton3" "3"

Also, two finger scroll started working. I had no idea that my touchpad supports it. The documentation however specifies a config for Alps touchpads. I read through synaptics configuration on Arch wiki to configure the touchpad to suit my usage. The Gentoo wiki also provides a number of configurations, in case you want to try things out. The AccelFactor value mentioned in these wikis turns out to be too slow for me. So, I increased its value. 

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