Raspberry pi eGalax touchscreen calibration on zero / Raspberry pi 3 / PIXEL

Software updates bring compatibility problems, that's just how it is. Although the eGalax touch screen drivers are now in the kernel, and the touch screen functionality works out of the box, I couldn't get the touch calibrated.

Long story short, this is what I ended up with. Sometime xinput_calibrator came out with a section like this :

 Section "InputClass"
        Identifier      "calibration"
        MatchProduct    "eGalax Inc. USB TouchController"
        Option  "MinX"  "2881"
        Option  "MaxX"  "62736"
        Option  "MinY"  "60381"
        Option  "MaxY"  "5495"
        Option  "SwapXY"        "0" # unless it was already set to 1
        Option  "InvertX"       "0"  # unless it was already set
        Option  "InvertY"       "0"  # unless it was already set
 EndSection

but that was no good!

Then, finally, it came out with a section like this:

 Section "InputClass"

        Identifier      "calibration"

        MatchProduct    "eGalax Inc. USB TouchController"

        Option  "Calibration"   "103 1962 1864 158"

        Option  "SwapAxes"      "0"

 EndSection

with the "Option Calibration stuff on one line, and this seemed to work. I put it in /usr/share/X11/xorg.conf.d/99-calibration.conf

Hope that saves someone else the time :)