How to make the screen brightness keys work again in KDE: Difference between revisions
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First, we have to find the screen device, which is located somewhere in the /sys/devices/pci0000:00 directory. | First, we have to find the screen device, which is located somewhere in the /sys/devices/pci0000:00 directory. | ||
Somewhere in this directory is a file located with the name 'brightness'. Let's find it. | Somewhere in this directory is a file located with the name 'brightness'. Let's find it. So, as root: | ||
#find /sys/devices/pci0000:00 -name "brightness" | # find /sys/devices/pci0000:00 -name "brightness" | ||
/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness | /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness | ||
/sys/devices/pci0000:00/0000:00:1c.2/0000:24:00.1/leds/mmc0::/brightness | /sys/devices/pci0000:00/0000:00:1c.2/0000:24:00.1/leds/mmc0::/brightness | ||
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When you read the content of the 'file', you get the current brightness level: | When you read the content of the 'file', you get the current brightness level: | ||
#cat /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness | # cat /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness | ||
235 | 235 | ||
The value lies somewhere between 0 and 255, it's a one byte value. | The value lies somewhere between 0 and 255, it's a one byte value. | ||
You can test if this work for you by writing a different value to that file: ( | You can test if this work for you by writing (still as root) a different value to that file: (remember to substitute the file for your graphics card) | ||
#echo 200 > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness | # echo 200 > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness | ||
If this works, you should see the brightness change, and you can go to the next step. | If this works, you should see the brightness change, and you can go to the next step. | ||
I created a simple QAD(quick and Dirty) 3 line script to read that value and increase it: | I created a simple QAD(quick and Dirty) 3 line script to read that value and increase it. | ||
I put the script in my home user's bin directory: | |||
user> vi ~/bin/brp | |||
<pre> | <pre> | ||
br=$(cat /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness) | br=$(cat /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness) | ||
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</pre> | </pre> | ||
I called it 'brp' which is nice and short and stands for ''''br'''ightness '''p'''lus' | |||
Note that I increase the value by 10 otherwise it would not change enough. You can vary that value of course to get finer control or get faster adjustment. | Note that I increase the value by 10 otherwise it would not change enough. You can vary that value of course to get finer control or get faster adjustment. | ||
I created a similar script called brm which decreases the value: | I created a similar script called brm which decreases the value: | ||
Revision as of 15:41, 9 November 2015
How to make button for screen brightness work on your laptop in KDE
When I started using a newer kernel in openSUSE 13.2, I noticed the buttons for screen brightness were no longer functioning on my laptop. This is verry annoying, so I decided to do something about it. I am using KDE. I will try to write the instructions as generic as possible, so that it will hopefully work in your situation too. This is a HP ELitebook 8570p.
First, we have to find the screen device, which is located somewhere in the /sys/devices/pci0000:00 directory.
Somewhere in this directory is a file located with the name 'brightness'. Let's find it. So, as root:
# find /sys/devices/pci0000:00 -name "brightness" /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness /sys/devices/pci0000:00/0000:00:1c.2/0000:24:00.1/leds/mmc0::/brightness /sys/devices/pci0000:00/0000:00:1c.3/0000:25:00.0/leds/phy0-led/brightness
Remember, your output is probably different from what I got here.
I have a radeon card, so the first line contains the device we will be working with.
When you read the content of the 'file', you get the current brightness level:
# cat /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness 235
The value lies somewhere between 0 and 255, it's a one byte value.
You can test if this work for you by writing (still as root) a different value to that file: (remember to substitute the file for your graphics card)
# echo 200 > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness
If this works, you should see the brightness change, and you can go to the next step.
I created a simple QAD(quick and Dirty) 3 line script to read that value and increase it.
I put the script in my home user's bin directory:
user> vi ~/bin/brp
br=$(cat /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness) br=$((br+10)) echo $br > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness
I called it 'brp' which is nice and short and stands for 'brightness plus' Note that I increase the value by 10 otherwise it would not change enough. You can vary that value of course to get finer control or get faster adjustment.
I created a similar script called brm which decreases the value:
user> vi ~/bin/brm
And paste the content
br=$(cat /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness) br=$((br-10)) echo $br > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightnessNow, the problem is that this file /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/radeon_bl0/brightness may only be written by root. Notice that all commands manipulating the file so far have been executed as root.