Ytdyklly

I'm running 16.04 on my X1 Yoga OLED.

I can't change the brightness of the screen at all, it seems to be on maximum brightness all the time. I've tried:

• 
  Fn+F5/F6
  


• 
  xbacklight -set 50(and 100, and 0, and 20, ...)/xbacklight -dec 10
  

I'm using GNOME Shell in Xorg.

Hopefully useful list of software and versions, tell me in the comments if you need more.

gnome-shell 3.18.5-0ubuntu0.1

tlp         0.9-1~xenial

tp-smapi    0.41-1

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

I did a similar thing to the above in Ubuntu MATE 17.04:

1. 
   cat $MYDIR/scrbr.property = 0.5 (scrbr = screen-brightness)
   


2. Created a script scrbr.sh:

```

#!/bin/bash



ACTION=$1



PROP_FILE=$MYDIR/scrbr.property

BRIGHT=$(cat $PROP_FILE)



if [[ "$ACTION" == "--up" ]]; then

        SYM="+"

elif [[ "$ACTION" == "--down" ]]; then

        SYM="-"

fi



BRIGHT=$(echo "$BRIGHT $SYM 0.1" | bc)



# Not less than 0

[[ $BRIGHT == -* ]] && BRIGHT=0



echo $BRIGHT > $PROP_FILE



xrandr --output eDP-1 --brightness $BRIGHT

3. Remap keys WinKey + Up to scrbr.sh --up, and same for --down.




4. Profit.

I needed a few tweaks to make @Redsandro solution work on my ubuntu 18.10 install.

Specifically, the Xauth root workaround doesn't work (thanks for mentioning that @Ivo B!) as the .Xauthority file no longer exists.

Using

$ xauth info

We see that the file is now at
/run/user/1000/gdm/Xauthority

Therefore we change the relevant line to

export XAUTHORITY=/run/user/1000/gdm/Xauthority

Additionally, I also had to change eDP1 to eDP-1.

In total this led to changes on three lines.

Additional notes

In order to debug, I used

rui@chaiX1YG2:/var/log$ $ tail -f /var/log/syslog | grep oled-br

e.g. for the two respective errors I found

Jan 16 13:03:01 chaiX1YG2 oled-brightness: Can't open display :0.0

Jan 16 13:03:01 chaiX1YG2 oled-brightness: No protocol specified

Jan 16 13:23:46 chaiX1YG2 oled-brightness: warning: output eDP1 not found; ignoring

Jan 16 13:23:46 chaiX1YG2 oled-brightness: xrandr: Need crtc to set gamma on.

NOTE also, this solution does not work in wayland! As xrandr does not work on wayland. So make sure when you log in, you choose xorg, not wayland),

(A bit unfortunate as for me, firefox touch events only works in Wayland, so I have to choose between the brightness vs firefox touchscroll. Not sure why that is yet).

(This answer would have been a comment but I lack credits.)