eGalaxTouch EXC7200 touch click problem

Maarten Vergouwe mvergouwe at
Fri Nov 22 06:26:57 PST 2013

I actually "worked around" the problem.
I've written a little daemon that grabs the kernel event driver and creates
a new input driver (via uinput) with the same capabilities.
In the daemon, I simply forward all events coming from the original driver
to the user driver, but when a BTN_TOUCH event is received I add a small
sleep (currently the minimum sleep I need is 85 ms - which is not so small
actually). This way there's no lockup in events (in fact I measure it in
the javascript events in Chromium, which is the real use case) and
everything goes fine.

Next up is looking at evdev why BTN_TOUCH in my situation behaves
differently from BTN_LEFT coming from a mouse (no problem there).

> I'm having a hard time with the following problem concerning an
> eGalaxTouch device.
> At first sight, everything seems to be working fine using the evdev driver
> with libmtdev. I have no problem with pinch/zoom etc. But after a short
> time Xserver emits button-press events immediately after button-release,
> even when you do a simple single tap.
> So tapping once on the screen results in "button-press" - "button-release"
> - "button-press". This makes any application behave strangely or it even
> gets stuck.
> I've written a simple test application printing the "ButtonPress" and
> "ButtonRelease" events coming from the X server (looping over XNextEvent)
> and the problem is evident. I can get X to behave correctly again by
> clicking a normal mouse. But using the touchscreen will almost immediately
> get it in the wrong state again.
> mtdev-test from libmtdev shows no problems at all and evtest also not, so
> I'm pretty sure it's a problem in X or evdev_drv (I didn't find a way to
> hook onto evdev yet). Both evtest and mtdev-test nicely emit button-press
> and button-release without extra events.
> Perhaps a similar issue was reported last year, but I don't know if there
> was any follow-up:
> Can someone share some insight, please?
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