Jumpy touch pad observation

[Richard A. Smith]

Gary C Martin wrote:
> Forgive me if I'm about to start an old wives tale, but I've  
> encountered the jumpy touch pad issues quite a lot on the B4 XO I have  
> here for testing. I'm currently running a recent joyride (2137) and  
> firmware (Q2D16) and am still encountering issues.
> 
> Observation: If the XO is fully charged and still plugged in to mains  
> supply the jumpiness can be very persistent, however if I unplug the  
> power adapter, the XO seems to then correctly re-calibrate within  
> seconds.

Its ground plane changes.  According to Alps we are supposed to be 
issuing a recal on AC insert/removal or and lid open.  And we don't do 
that yet in the chain of events.

A claim from Alps is that there is so little metal in the XO that the 
ground plane capacitance has a really large variance based on its 
environment and whats plugged up to it.  Even after we added more metal 
in the frame to help.  So your observation falls in line with known data 
from the mfg.

If you are plugged up to mains and its jumpy does a 4 finger recal fix it?

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.

-- 
Richard Smith  <richard at laptop.org>
One Laptop Per Child