From ede73619ea7c4a319dc15d1b4b7234bbc66f61e0 Mon Sep 17 00:00:00 2001
From: Jordan <jordan.ruthe@gmail.com>
Date: Sun, 20 Jun 2021 20:27:07 -0400
Subject: [PATCH] docs: Touchscreen rotation configuration

---
 docs/Installation.md | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/docs/Installation.md b/docs/Installation.md
index a6b68c82..bc40bcc6 100644
--- a/docs/Installation.md
+++ b/docs/Installation.md
@@ -69,3 +69,40 @@ Find the ID of your display and put it in the following command:
 ```
 DISPLAY=:0 xinput_calibrator -v --device <id from last command>
 ```
+
+#### Touchscreen touch rotation
+If your touchscreen isn't registering touches properly after the screen has been rotated, you will need to apply a
+transformation matrix. You can have the matrix be one of the following:
+0°: `1 0 0 0 1 0 0 0 1`
+90° Clockwise: `0 -1 1 1 0 0 0 0 1`
+90° Counter-Clockwise: `0 1 0 -1 0 1 0 0 1`
+180°: `-1 0 1 0 -1 1 0 0 1`
+
+To check the current matrix, you will need your `<screen name>` (which can be found via the last section, ex:
+"wch.cn USB2IIC_CTP_CONTROL"). Run the following command:
+`xinput list-props "wch.cn USB2IIC_CTP_CONTROL"`
+
+It will output something such as:
+```
+Device '<screen name>':
+        Device Enabled (115):   1
+        Coordinate Transformation Matrix (116): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000
+        libinput Calibration Matrix (247):      -1.000000, 0.000000, 1.000000, 0.000000, -1.000000, 1.000000, 0.000000, 0.000000, 1.000000
+        libinput Calibration Matrix Default (248):      -1.000000, 0.000000, 1.000000, 0.000000, -1.000000, 1.000000, 0.000000, 0.000000, 1.000000
+        libinput Send Events Modes Available (249):     1, 0
+        libinput Send Events Mode Enabled (250):        0, 0
+        libinput Send Events Mode Enabled Default (251):        0, 0
+        Device Node (252):      "/dev/input/event0"
+        Device Product ID (253):        6790, 58083
+```
+
+You can verify by checking that the 'Coordinate Transformation Matrix' or 'libinput Calibration Matrix'.
+
+You can test a change by running:
+`xinput set-props "<screen name>" 'Coordinate Transformation Matrix' <matrix>`
+Replace matrix with one of the options above, such as: `1 0 0 0 1 0 0 0 1`
+
+To make this permanent, modify the file `/etc/udev/rules.d/51-touchscreen.rules` and put the following line in:
+```
+ACTION=="add", ATTRS{name}=="<screen name>", ENV{LIBINPUT_CALIBRATION_MATRIX}="<matrix>"
+```