(resend) evtouch questions (xorg 6.8.2)

McDonald, Michael-p7438c Michael.McDonald at gdc4s.com
Thu Mar 25 10:59:09 PDT 2010

I'm resending this as it hasn't made it back thru the list to me.

Mike McDonald

-----Original Message-----
From: McDonald, Michael-p7438c 
Sent: Wednesday, March 24, 2010 7:08 PM
To: xorg at lists.freedesktop.org
Subject: evtouch questions (xorg 6.8.2)

We're trying to integrate an eGalax touch screen into our 
system and we're running into a few issues. We're using 
xorg-x11 6.8.2 from RHEL4 with touchkitusb.c and evtouch 
(0.8.0) from RHEL5 (xorg 7.1). This bizarre combo seemed like 
the best option for getting the touch screen to work with 
RHEL4 without using the binary blob from eGalax. (No, we 
cannot update Xorg nor the kernel.)

1) The sequence of X events we get are not correct when you 
press and release the touch screen. We get a ButtonPress at 
the current cursor location (where ever that might be!), 
followed by a PointerMotion to the pressed location, followed 
by a ButtonRlease at the correct location. We have "fixed" 
this by reporting the X and Y values before the key event in 
the touchkitusb.c driver. Has anyone else seen this behaviour 
and how did you fix it?

2) The touch screen doesn't seem to be debounced. We almost 
always get multiple press/release sequences whenever you 
touch the screen. There doesn't appear to be any debounce 
code in either of the drivers. Do all touch screens bounce? 
How should we attempt to debounce the touch screen?

3) Is there anyway to get evtouch to reread the calibration 
file without restarting X? ev_calibrate will generate a new 
calibration file for us but I don't see anything in evtouch 
that will reload it.

4) Is there anyway to conditionally configure the evtouch 
driver in the xorg.conf file? Some of our systems have touch 
screens and some do not. If you have the evtouch driver 
configured into the xorg.conf file but don't have a touch 
screen connected, X will not start. I've attached our xorg.conf file.


Mike McDonald
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