kernel patch for Synaptics Touchpads
jay at oneway.com
Fri Dec 24 10:54:48 PST 2004
I've spent the last few days tweaking psm.c to better support the
synaptics touchpad in my Acer laptop. I now have it to a point that
I'm happy with it, and since I've seen a fair amount of interest in the
synaptics touchpad on this list - I figured I'd share the patch with
anyone who wants it.
This patch adds extended button support ( on mine the scroll-button is
now fully supported both horizontal and vertical). It also adds
sysctl's to control tapping thresholds (allows you to turn tapping off
/ make it harder to 'accidentally' tap). Finally - it helps with the
'sticking' problem with the current driver - Low speed movements work
The patch is against 184.108.40.206 psm.c (what is in 5.3-RELEASE) and is
I tried to set reasonable defaults, below are the tunable parameters:
Touchpad tap threshold - the higher this number - the harder it is to
tap. 120+ effectively turns off tapping.
Touchpad timeout - how long we have to wait between mouse movement
and a tap before a tap is registered as a click.
if non-zero, the directional pad scrolls, otherwise all buttons
register as a middle-click.
the number of touchpad units below-which we go into low-speed
the number of touchpad units below which we ignore altogether.
level at which we squelch movement packets. This effectively sends 1
out of every
synaptics_squelch_level packets when running in low-speed mode.
sysctl hw.psm will show the defaults, which seem just about right on my
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