From 92db7feab8d6bfdae2ba3f37fe57d54e4e2d0040 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Paul=20H=C3=A4nsch?= <paul@plutz.net>
Date: Mon, 5 Oct 2020 17:24:43 +0200
Subject: [PATCH] support for waveshare 4inch display (rev A)

---
 modules/display_wsLCD4.mk        |  77 +++++++++++++++++++++++++++++++
 modules/waveshare35a-overlay.dtb | Bin 0 -> 2610 bytes
 2 files changed, 77 insertions(+)
 create mode 100644 modules/display_wsLCD4.mk
 create mode 100644 modules/waveshare35a-overlay.dtb

diff --git a/modules/display_wsLCD4.mk b/modules/display_wsLCD4.mk
new file mode 100644
index 0000000..7c32cf5
--- /dev/null
+++ b/modules/display_wsLCD4.mk
@@ -0,0 +1,77 @@
+PACKAGES += xserver-xorg-input-evdev xinput xinput-calibrator
+
+define RPICONFIG +=
+
+### Waveshare 4 Inch Display ###
+hdmi_force_hotplug=1
+dtparam=i2c_arm=on
+dtparam=spi=on
+enable_uart=1
+dtoverlay=waveshare35a
+# dtoverlay=ads7846,cs=1,penirq=25,penirq_pull=2,speed=50000,keep_vref_on=0,swapxy=0,pmax=255,xohms=150,xmin=200,xmax=3900,ymin=200,ymax=3900
+hdmi_group=2
+hdmi_mode=1
+hdmi_mode=87
+hdmi_cvt 430 320 60 6 0 0 0
+hdmi_drive=2
+display_rotate=0
+endef
+
+export display_wsLCD4_cfg display_wsLCD4_rotation
+
+define display_wsLCD4_cfg :=
+Section "InputClass"
+	Identifier	"calibration"
+	MatchProduct	"ADS7846 Touchscreen"
+	Option	"Calibration"	"3950 172 3871 194"
+	Option	"SwapAxes"	"1"
+	Option	"EmulateThirdButton"	"1"
+	Option	"EmulateThirdButtonTimeout"	"1000"
+	Option	"EmulateThirdButtonMoveThreshold"	"300"
+
+	# Identifier "evdev touchscreen catchall"
+	# MatchIsTouchscreen "on"
+	# Option  "Calibration"   "200 3950 250 4000"
+	# MatchDevicePath "/dev/input/event*"
+	# Driver "evdev"
+EndSection
+endef
+
+define display_wsLCD4_rotation :=
+# Keep touch matrix rotated in accordance with screen rotation
+while sleep 3; do
+  oldrotate="$${rotate}"
+  rotate="$$(xrandr |grep primary)"
+  rotate="$${rotate#*+0+0 }"
+  rotate="$${rotate% (*}"
+
+  [ "$${oldrotate}" = "$${rotate}" ] || case $$rotate in
+    left)     xinput set-prop 'ADS7846 Touchscreen' 'Coordinate Transformation Matrix' 0 -1 1  1 0 0  0 0 1;;
+    right)    xinput set-prop 'ADS7846 Touchscreen' 'Coordinate Transformation Matrix' 0 1 0  -1 0 1  0 0 1;;
+    inverted) xinput set-prop 'ADS7846 Touchscreen' 'Coordinate Transformation Matrix' -1 0 1  0 -1 1  0 0 1;;
+    *)        xinput set-prop 'ADS7846 Touchscreen' 'Coordinate Transformation Matrix' 1 0 0  0 1 0  0 0 1;;
+  esac
+done &
+endef
+
+.PHONY: _display_wsLCD4
+_config: _display_wsLCD5 ${CFGROOT}/boot/waveshare35a.dtbo
+_display_wsLCD4: ${CFGROOT} _copy _mount
+	# Rough touch calibration
+	mkdir -p "$${CFGROOT}/usr/share/X11/xorg.conf.d/"
+	printf '%s\n' "$${display_wsLCD4_cfg}" >"$${CFGROOT}/usr/share/X11/xorg.conf.d/45-evdev.conf"
+	# Resolution / Rotation stuff
+	mkdir -p "$${CFGROOT}/etc/X11/Xsession.d/"
+	printf 'xrandr --size 480x320\n' >"$${CFGROOT}/etc/X11/Xsession.d/10display_resolution"
+	printf '%s\n' "$$display_wsLCD4_rotation" >"$${CFGROOT}/etc/X11/Xsession.d/20touch_rotation"
+	# Correct DPI scaling, although application support is mediocre
+	mkdir -p "$${CFGROOT}/etc/X11/Xresources/"
+	printf 'Xft.dpi: 144\n' >"$${CFGROOT}/etc/X11/Xresources/dpi_resolution"
+	# Workaround for applications that do not handle DPI scaling correctly
+	-sed -i 's;^Exec=;Exec=env GDK_DPI_SCALE=.5 ;' \
+	  $${CFGROOT}/usr/share/applications/chromium*.desktop \
+	  $${CFGROOT}/usr/share/applications/firefox*.desktop \
+	  $${CFGROOT}/usr/share/applications/exo-web-browser.desktop
+
+${CFGROOT}/boot/waveshare35a.dtbo: modules/waveshare35a-overlay.dtb
+	cp "$<" "$@"
diff --git a/modules/waveshare35a-overlay.dtb b/modules/waveshare35a-overlay.dtb
new file mode 100644
index 0000000000000000000000000000000000000000..9f082e463c72cb8aafd60aaa9ca3709cc214f7fa
GIT binary patch
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literal 0
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-- 
2.39.2