#!/bin/sh

# This script toggles ALPM (Agressive Link Power Management) when on
# battery for all SATA AHCI controllers that support it.

# Don't do anything if there's no controllers with the feature
test ! -z "/sys/class/scsi_host/host*/link_power_management_policy" || exit 0

case "$1" in
	true)
		echo "**SATA ALPM power savings ON"
		val=min_power
		;;
	false)
		echo "**SATA ALPM power savings OFF"
		val=max_performance
		;;
	*)
		echo "**Called with unknown arg \"$1\" (should be true/false)"
		exit 1
		;;
esac

for ctl in /sys/class/scsi_host/host*/link_power_management_policy; do
	echo $val > $ctl
done

exit 0