Jumpy touch pad observation

Andres Salomon dilinger at queued.net
Fri Jul 11 16:01:54 EDT 2008

On Fri, 11 Jul 2008 19:43:33 +0100
Gary C Martin <gary at garycmartin.com> wrote:

> With the latest Joyride changes, it seems much clearer/easier to see  
> when the driver is trying to re-calibrate as the pointer suddenly  
> stops moving for a few seconds. In the persistent case (plugged in &  
> charged), leaving the touch pad alone to allow calibration to
> complete usually does not work, and the cursor continues to jump (or
> float when your finger is near but not touching the surface) when you
> try to use it again. Unplug the AC, and the auto re-calibration
> usually[2] succeeds.

Wow, that's pretty bizarre.  Given that I did most of my testing on the
driver while plugged in, and I have yet to see it fail to recalibrate,
I'd expect it to be the other way around.

> > Either way when its jumpy please enable kern.* logging in /etc/ 
> > rsyslog.conf, route it to a file, and restart rsyslogd.  Then echo
> > 1  
> > > /sys/module/psmouse/parameters/tpdebug
> > Then use the mouse jumpy for a while and send me, dilinger, or  
> > deepak the log file for us to look at.
> OK, will do. Thanks for you feedback.

Even without debugging turned on, dmesg should show messages about
recalibration and detection of jumpiness or spew.  If you're seeing the
cursor act strangely, but we're _not_ detecting it, I'm especially
interested in those logs.  If the recalibration is simply failing..
well, I'm not really sure what to do about that, short of power
cycling (which will turn off the keyboard momentarily as well.  It's

> [1] The common case seems to be touching the pad in two places in  
> quick succession, this is easily done when trying to use the left or  
> right mouse buttons while moving the pointer as they are placed so  
> near the touch surface. I often hit this when using the drag
> metaphor (probably what makes arranging activities on the new random
> home screen layout feel more frustrating than it should be).
> [2] I think the cases I've seen where it does not succeed are down
> to damp hands, greasy/wet smear somewhere on pad, perhaps nylon  
> underpants (I'm joking!)

Does going without underpants make a difference?  Perhaps some aluminum
foil underpants will help greatly with grounding issues.  Richard, can
we make clothing requirements for XO usage?

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