synaptics: Motion history change in b26125e412a130b7a8f8b6adf9ffc8e9cc8df42c

Chase Douglas chase.douglas at
Wed Jan 11 08:43:52 PST 2012

In Ubuntu, we have been shipping xf86-input-synaptics 1.4.1. Now we are
upgrading to the latest code (which I hope to add multitouch support to
soon). We noticed that the pointer speed is much faster now, across
devices. When I reverted commit
b26125e412a130b7a8f8b6adf9ffc8e9cc8df42c, things seemed to return to the
way they were. This is the commit message:


Replace the motion estimator

Use a smarter motion estimator that attempts to draw a best-fit line
through the history where possible, including taking acceleration into


We feel the speed is too fast for a default, but I'm not sure how to
best resolve the issue. I don't see any knobs that would affect the
algorithm, so if we want to slow things down I'm not sure which knob
would be best to turn.

Any thoughts?

-- Chase

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