Lenovo ThinkPad X1 Yoga OLED Brightness

There is no backlight with an OLED screen. So the normal methods do not work. Adjust screen brightness by way of:

xrandr --output eDP1 --brightness .5  # dim to half 

xrandr --output eDP1 --brightness 1  # no dimming

the number can be anything between 0 and 1

I've been looking for a way to run the xrandr command when pressing the brightness buttons. I created custom acpi events for that (more info on that here: https://help.ubuntu.com/community/LaptopSpecialKeys ). This is still a hack and no proper solution, but it works for me:

I created three files, /etc/acpi/events/yoga-brightness-up:

event=video/brightnessup BRTUP 00000086
action=/etc/acpi/yoga-brightness.sh up

and /etc/acpi/events/yoga-brightness-down:

event=video/brightnessdown BRTDN 00000087
action=/etc/acpi/yoga-brightness.sh down

and finally /etc/acpi/yoga-brightness.sh:

#!/bin/sh

# Where the backlight brightness is stored
BR_DIR="/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/"


test -d "$BR_DIR" || exit 0

MIN=0
MAX=$(cat "$BR_DIR/max_brightness")
VAL=$(cat "$BR_DIR/brightness")

if [ "$1" = down ]; then
    VAL=$((VAL-71))
else
    VAL=$((VAL+71))
fi

if [ "$VAL" -lt $MIN ]; then
    VAL=$MIN
elif [ "$VAL" -gt $MAX ]; then
    VAL=$MAX
fi

PERCENT=`echo "$VAL / $MAX" | bc -l`

export XAUTHORITY=/home/ivo/.Xauthority  # CHANGE "ivo" TO YOUR USER
export DISPLAY=:0.0

echo "xrandr --output eDP-1 --brightness $PERCENT" > /tmp/yoga-brightness.log
xrandr --output eDP-1 --brightness $PERCENT

echo $VAL > "$BR_DIR/brightness"

which is heavily inspired by the file asus-keyboard-backlight.sh and the information on https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/660901 for the xrandr root-access problem.

Don't forget to restart acpi by typing

sudo service acpid reload

I hope, this helps ;-)

Smooth Brightness Control

(Update: I've uploaded the provision script to automate this to Github.)

This script is based on the workaround by Ivo Blöchliger. I'd hate for my expensive laptop to look cheap, so I need a smooth transition between brightness values to compete with my non-linux colleagues.

This is created for and tested on Linux Mint 18.3 and Ubuntu 16.04.3 on a Lenovo ThinkPad X1 Yoga (2nd Gen) with OLED panel.

/etc/acpi/events/oled-brightness-up (644):

event=video/brightnessup BRTUP 00000086
action=/etc/acpi/oled-brightness.sh up

/etc/acpi/events/oled-brightness-down (644):

event=video/brightnessdown BRTDN 00000087
action=/etc/acpi/oled-brightness.sh down

/etc/acpi/oled-brightness.sh (755):

#!/bin/bash
# Smooth brightness control
# Change "redsandro" in the line below to your username
export XAUTHORITY=/home/redsandro/.Xauthority
export DISPLAY=:0.0

OLED_BR=`xrandr --verbose | grep -i brightness | cut -f2 -d ' '`
CURR=`LC_ALL=C /usr/bin/printf "%.*f" 1 $OLED_BR`

MIN=0
MAX=1.2

if [ "$1" == "up" ]; then
    VAL=`echo "scale=1; $CURR+0.1" | bc`
else
    VAL=`echo "scale=1; $CURR-0.1" | bc`
fi

if (( `echo "$VAL < $MIN" | bc -l` )); then
    VAL=$MIN
elif (( `echo "$VAL > $MAX" | bc -l` )); then
    VAL=$MAX
else
    if [ "$1" == "up" ]; then
        for I in {1..10..1}; do xrandr --output eDP1 --brightness `echo "scale=2; $I/100+$CURR" | bc` 2>&1 >/dev/null | logger -t oled-brightness; done
    else
        for I in {1..10..1}; do xrandr --output eDP1 --brightness `echo "scale=2; $CURR-$I/100" | bc` 2>&1 >/dev/null | logger -t oled-brightness; done
    fi
fi

# Set Intel backlight to fake value
# to sync OSD brightness indicator to actual brightness
INTEL_PANEL="/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/"
if [ -d "$INTEL_PANEL" ]; then
    PERCENT=`echo "scale=4; $VAL/$MAX" | bc -l`
    INTEL_MAX=$(cat "$INTEL_PANEL/max_brightness")
    INTEL_BRIGHTNESS=`echo "scale=4; $PERCENT*$INTEL_MAX" | bc -l`
    INTEL_BRIGHTNESS=`LC_ALL=C /usr/bin/printf "%.*f" 0 $INTEL_BRIGHTNESS`
    echo $INTEL_BRIGHTNESS > "$INTEL_PANEL/brightness"
fi

Remove any previous brightness handlers, and finally, do sudo service acpid reload