Dell 5500 resume backlight fix in Ubuntu

fixbacklight

#!/bin/sh
# From patchwork.freedesktop.org/.../
# and en.community.dell.com/.../19985320
# /lib/systemd/system-sleep/fixbacklight
# Suspend Resume fails to restore PWM_GRANUALITY
# Based on script by [email protected]

INTEL_REG=/usr/bin/intel_reg
ADDR="0x000c2000"
SAVE_FILE=/var/lib/systemd/save_intel_reg_pwm_granuality

[ -x "$INTEL_REG" ] || exit 0

case "$1" in
        pre)
		echo "$0: Saving Intel Register PWM_GRANUALITY"
		"$INTEL_REG" read "$ADDR" \
			| (read addr value && echo "$value") \
			>"$SAVE_FILE"
	sync
	;;
	post)
		value=`cat "$SAVE_FILE" 2>/dev/null`
		if [ -n "$value" ]
		then
			echo "$0: Restoring Intel Register PWM_GRANUALITY $value"
			"$INTEL_REG" write "$ADDR" "$value"
			rm "$SAVE_FILE"
		fi
	;;
esac