Disable touchscreen area (root available)

My rooted Xperia Z1 on Android 5.1 has a broken touchscreen area in the upper half of the screen.

I was able to partly solve the problem by following this SO question: Resize screen for Dead touch zone

My problem is: The broken area constantly sends touch events. By that, I am not able to input any touch events myself.

How can I filter any touch events in the upper half of my screen?