How to setup x11 touchscreen in linux desktop?

I am using opensuse desktop with two screens, top and bottom. Only the bottom screen is touchscreen, which is USB touchscreen. Both monitors are used as a single screen. I tried to configure the touch screen via xorg.conf file using the following parameters for InputDevice:

Section "InputDevice"
  Driver       "evdev"
  Identifier   "touchscreen"
  Option       "Device" "/dev/input/event3"
  Option       "Name" "Kortek touch screen"
  #Option      "GrabDevice" "true"
  Option       "InvertY" "true"
  Option       "Calibration 0 4095 0 4095"
  Option       "Emulate3Buttons" "true"
  Option       "Emulate3Timeout"     "50"
EndSection

Using this I can see the touch events as the mouse cursor moves. But the Y coordinates are not correct. x cooridates are fine. But Y coordinates pan upto the top-edge of the top screen, while I move my finder to the top-edge of bottom screen.

Now, after reading through various articles on internet, I came across this website : http://ift.tt/1BXwj55 It talks about "Transformation Matrix". I tried to use it but Y coordinates are still wrong.

I noticed that when I plug off the top screen and re-enter the x window desktop, after logging out. The touch coordinates are correct.

So, I want to know what is wrong with my configuration.

I also noticed that the calibration coordinates returned from "xinput calibrator" are 0 4095 0 4095 , which are MinX,MaxX,MinY,MaxY. But my real screen resolution is 1920x1080(for each monitors).