dell XPS9560 cpufreq fix for acpi-cpufreq

dell-xps9560-linux-cpufreq.sh

#!/bin/sh

base="/sys/devices/system/cpu/cpufreq/policy0/"

ME="${0}"
SCALING_DRIVER="$(<${base}/scaling_driver)"
SCALING_GOVERNOR="$(<${base}/scaling_governor)"
AC_ONLINE=$(</sys/class/power_supply/AC/online)

# install this script in udev
UDEV_RULES_FILE="/etc/udev/rules.d/81-xps9560-cpufreq.rules"
if [ ! -f ${UDEV_RULES_FILE} ]
then
	echo >&2 "Installing this script at ${UDEV_RULES_FILE}"
	cat >${UDEV_RULES_FILE} <<EOF
SUBSYSTEM=="power_supply", ENV{POWER_SUPPLY_ONLINE}=="0", RUN+="${ME}"
SUBSYSTEM=="power_supply", ENV{POWER_SUPPLY_ONLINE}=="1", RUN+="${ME}"
EOF
	udevadm control --reload-rules
fi

ignore_ppc() {
	[ "$(</sys/module/processor/parameters/ignore_ppc)" = "1" ] && return 0

	printf >&2 "Instructing the kernel to ignore the max CPU freq enforced by the BIOS... "

	echo 1 >/sys/module/processor/parameters/ignore_ppc

	if [ "$(</sys/module/processor/parameters/ignore_ppc)" != "1" ]
		then
		echo >&2 "FAILED"
	else
		echo >&2 "OK"
	fi
}

set_energy_bias() {
	# MSR_IA32_ENERGY_PERF_BIAS
	# 0 is "maximum performance" and 15 is "maximum energy efficiency"
	local bias="${1}"

	[ $(( bias + 1 - 1 )) -lt 0  ] && bias=0
	[ $(( bias + 1 - 1 )) -gt 15 ] && bias=15

	cpupower set -b ${bias}
}

set_core_attribute() {
	local dir="${1}" attribute="${2}" value="${3}"

	[ "$(<${dir}/${attribute})" = "${value}" ] && return 0

	printf >&2 "Setting ${1}/${attribute} to ${value}... "
	echo >${dir}/${attribute} "${value}"

	if [ "$(<${dir}/${attribute})" != "${value}" ]
		then
		echo >&2 "FAILED"
		return 1
	else
		echo >&2 "OK"
		return 0
	fi
}

foreach_core() {
	local cmd="${1}"
	shift

	for x in /sys/devices/system/cpu/cpu*/cpufreq
	do
		"${cmd}" "${x}" "${@}"
	done
}

case "${SCALING_DRIVER}" in
	acpi-cpufreq)
		SCALING_AVAILABLE_FREQUENCIES=( $(<${base}/scaling_available_frequencies) )
		SCALING_MAX_FREQ="$(<${base}/scaling_max_freq)"

		# on Dell XPS9560, the BIOS limits the CPU to 1.5GHz - fix it
		ignore_ppc

		if [ ${AC_ONLINE} -eq 0 ]
			then
			echo >&2 "Powersaving settings"
			logger -p info "Powersaving settings"
			governor="powersave"

			# use the 2nd max frequency the processor supports
			# (ie disable turbo)
			max_frequency="${SCALING_AVAILABLE_FREQUENCIES[1]}"
		else
			echo >&2 "Performance settings"
			logger -p info "Performance settings"
			governor="ondemand"

			# use the max frequency the processor supports
			max_frequency="${SCALING_AVAILABLE_FREQUENCIES[0]}"
		fi

		foreach_core set_core_attribute scaling_governor "${governor}"
		foreach_core set_core_attribute scaling_max_freq "${max_frequency}"
		echo >&2 "Done"
		;;

	intel_pstate)
		echo >&2 "Using scaling driver: ${SCALING_DRIVER}"
		echo >&2 "Add kernel boot option: intel_pstate=disable"

		if [ ${AC_ONLINE} -eq 0 ]
			then
			echo >&2 "Powersaving settings"
			logger -p info "Powersaving settings"
			energy_preference="balance_power"
		else
			echo >&2 "Performance settings"
			logger -p info "Performance settings"
			energy_preference="balance_performance"
		fi

		foreach_core set_core_attribute energy_performance_preference "${energy_preference}"
		;;

	*)
		echo >&2 "Unknown scaling driver: ${SCALING_DRIVER}"
		;;
esac