adding additional PWR Energy Savings

[rudiratlos]

I've wrote a script that uses some tweaks to bring power consumption further down.
Maybe you will find it usefull and use parts of the code (enable_pwrsave) directly in your startup script.
It's only:
/usr/bin/tvservice -o > /dev/null
/usr/bin/cpufreq-set -g powersave
additionally you have to:

1. install the sw-package cpufrequtils
2. add some parameters to /boot/config.txt
   this is done by calling the script with parameter setup
   (pls. see function setup_env)

calling the script with parameter status:
this will show the active cpu freq. set by the cpu governor

e.g.
current CPU frequency is 600 MHz (asserted by call to hardware).

have fun
regards Stefan

`#/bin/bash

V1.0 by SF 2022-07-27

inspired by: https://buyzero.de/blogs/news/raspberry-pi-strom-sparen-tipps-tricks

function setup_env {
fn="/boot/config.txt"
tm="# define minimum freq. for energy saving (used by cpu governor)"
grep -Fq "$tm" "$fn"
_ret=$?
if [ "$_ret" != "0" ]; then
if [ "$1" != "noswpkg" ]; then
apt-get -qy update
apt-get -qy install cpufrequtils
fi
echo " " >> $fn
echo "# Disable the PWR LED (save energy)" >> $fn
echo "dtparam=pwr_led_trigger=none" >> $fn
echo "dtparam=pwr_led_activelow=off" >> $fn
echo "$tm" >> $fn
echo "# use turbo speed for 20sec to speed up boot process" >> $fn
echo "initial_turbo=20" >> $fn
echo "force_turbo=0" >> $fn
echo "arm_freq_min=250" >> $fn
echo "core_freq_min=100" >> $fn
echo "sdram_freq_min=150" >> $fn
echo "over_voltage_min=0" >> $fn
fi
return 0
}

function enable_pwrsave {

enable pwr save, LEDs off, HDMI port off, set cpu to lower freq

echo 0 | tee /sys/class/leds/led0/brightness > /dev/null

echo 0 | tee /sys/class/leds/led1/brightness > /dev/null

/usr/bin/tvservice -o > /dev/null
/usr/bin/cpufreq-set -g powersave
_ret=$?
return $_ret
}

function disable_pwrsave {

disable pwr save, LEDs on, HDMI port on, set cpu to higher freq

echo 1 | tee /sys/class/leds/led0/brightness > /dev/null

echo 1 | tee /sys/class/leds/led1/brightness > /dev/null

/usr/bin/tvservice -p > /dev/null
/usr/bin/cpufreq-set -g performance
_ret=$?
return $_ret
}

ret=0
case "$1" in
setup)
setup_env "$2"
ret=$?
;;
start)
enable_pwrsave "$2"
ret=$?
;;
stop)
disable_pwrsave "$2"
ret=$?
;;
status)
/usr/bin/cpufreq-info "$2"
ret=$?
;;
)
echo "Usage: ${0##/} start | stop | status | setup [noswpkg]"
esac

exit $ret`

[rvt]

What sort of power savings are we getting ?