XPS Linux workarounds

xps-touchscreen-workaround.service

[Unit]
Description=Potentially dangerous fix touchscreen after resume on the XPS 13 9350
After=suspend.target

[Service]
Type=simple
ExecStart=/home/anthony/path/to/xps-touchscreen-workaround.sh

[Install]
WantedBy=suspend.target

xps-touchscreen-workaround.sh

#!/bin/bash

# Create a kill switch that will break this script when the installed kernel version breaks. There
# is already a patch for this in the linux kernel. No telling how something like this will interract
# with that. If your new kernel version still doesn't have the fix then update the WORKS_ON_KERNEL value
# with `uname -r` and the script will work again.
#
# Maililng list with patch: https://marc.info/?l=linux-gpio&m=147610677825233&w=2
# Commit on github: https://github.com/torvalds/linux/commit/c538b9436751a0be2e1246b48353bc23156bdbcc
WORKS_ON_KERNEL="4.4.0-47-generic"
if ! [ "$WORKS_ON_KERNEL" = "`uname -r`" ]; then
    echo "The kernel is no longer $WORKS_ON_KERNEL. This script has an 'if' that stops it from working when the kernel changes because the actual fix for this issue might be in your new kernel. If it isn't, then modify $0 to allow it to keep running."
    exit 1
fi

# On the XPS 13 9350, my pin is 103. Run the netire command without awk to see full output
PIN_NUMBER=`grep CPU_GP_1 /sys/kernel/debug/pinctrl/INT344B\:00/pins | awk '{print $2}'`

# This is the pin ranges. You need it to use the start of the ranges to properly address the right pin
STARTING_PIN=`cat /sys/kernel/debug/pinctrl/INT344B\:00/gpio-ranges | sed -n 's/.*GPIOS.*\[\(.*\) -.*PINS.*/\1/p'`

# This is the pin that we're actually going to request modifying
EFFECTIVE_PIN=$((STARTING_PIN + PIN_NUMBER))

echo "Determined $EFFECTIVE_PIN was the right pin because CPU_GP_1 was $PIN_NUMBER and the gpio range starts at $STARTING_PIN"

# First, we lock it
echo $EFFECTIVE_PIN > /sys/class/gpio/export

# Then, we set it to high (1). The entire issue was caused by it being set to low (0) by mistake during suspend
echo high > "/sys/class/gpio/gpio$EFFECTIVE_PIN/direction"

# Then we release the lock
echo $EFFECTIVE_PIN > /sys/class/gpio/unexport