Intel HD 4000 graphics brightness not working

English Hardware
1

Just as the title says, I have integrated Intel HD 4000 graphics on my laptop. The fn keys, nor the brightness slider will change the brightness.
I tried adding acpi_backlight=vendor to grub which didn’t work.
I currently have a workaround script with acpi echo’ing to /sys/class/backlight/intel_backlight/brightness

So, for example, this command will work in terminal:
echo 2800 > /sys/class/backlight/intel_backlight/brightness

Although acpi_video0 exists, changing it does not effect the brightness of the screen.
So, what can I do to make the brightness slider change the brightness (and hopefully, by default, enable the fn keys as they are supposed to work)?

2
  • basketthis

is this a Lenovo? If so, add thinkpad-acpi.brightness_enable=1 to the grub options, too.

Uwe

3

Thanks for the reply. It’s not. It’s a Sony Vaio. And only changing the intel_brightness/brightness value changes the brightness of the screen.

4

I ran into this on my HP laptop.

After some research, it appears that numerous manufacturers are coding their special function buttons using WMI (Windows Management Interface). Starting somewhere around 2009, a kernel WMI module was created to enable support for WMI functionality, but it’s up to each and every manufacturer to contribute the code necessary for this module to work on their hardware. The result is that support by every manufacturer is spotty and although I’m sure there is plenty of repetition for functions common to all manufacturers, “someone else” contribution won’t help you on your hardware.

So,
The bottom line is that you likely need to complain to Sony to work a little harder to contribute their hardware configuration definitions to the Linux kernel. The upside is that if Sony does actually fill your request, it’ll show up in a regular kernel eventually and work for you without any effort on your part.

TSU

5

Thanks for the reply. I was assuming that other users were able to come up with a solution which drove me to post here. Most of the time I am able to come up with a solution on my own after a bit of research. In fact, I find that to be one of the fascinating things about Linux is that any user can modify/fix/break/add/remove anything they like.
If contacting Sony is the answer, any suggestions on how I should go about asking for them to have an attempt at this?