Changes between Version 23 and Version 24 of ventana/LVDS

Timestamp:

10/13/2021 08:18:56 PM (4 years ago)

Author:

Tim Harvey

Comment:

added screen rotation example

ventana/LVDS

@@ -824 +824 @@
 While the code changes can be fairly simple, determining the timings can be complicated and involves translating timings from the manufacturers datasheet to the display timings that Linux drivers need.
 
+=== Handling Screen rotation
+As an example let's assume you have a touchscreen display using an edt-ft5x06 touch controller and your screen's display 0,0 agrees with the touch input 0,0 both in the top-right corner of the display (determined with evtest) but you want to rotate your screen 90deg clockwise to put it in 'portrait mode'. This would cause the x/y coordinates to be wrong requiring some mapping in the Linux input subsystem. This scenario would require us to 
+
+dt fragment:
+{{{
+&i2c3 { 
+        clock-frequency = <100000>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&pinctrl_i2c3>;
+        status = "okay";
+
+        touchscreen: touchscreen@38 {
+                compatible = "edt,edt-ft5406", "edt,edt-ft5x06";
+                pinctrl-names = "default";
+                pinctrl-0 = <&pinctrl_touch>;
+                reg = <0x38>;
+                interrupt-parent = <&gpio7>;
+                interrupts = <12 IRQ_TYPE_EDGE_FALLING>;
+                touchscreen-swapped-x-y;
+                touchscreen-inverted-y;
+                touchscreen-size-x = <1024>;
+                touchscreen-size-y = <600>;
+        };
+};
+
+&iomuxc {
+        pinctrl_touch: touchgrp {
+                fsl,pins = <
+                        MX6QDL_PAD_GPIO_17__GPIO7_IO12          0x1b0b0
+                >;
+        };
+};
+}}}
+
+Again, use the 'evdev' application to determine where the touch sensor's 0,0 coordinate is and make it match the display's 0,0. Hint, run 'evdev /dev/input/event0 | grep ABS_X' to show only the X coordinate then switch to the Y coordinate to help understand the mapping.
+
 === Determining Display Timing values