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I am having the common "missing brightness controller" problem in Ubuntu (no brightness controller in settings, or as a shortcut keys, brightness controller software does nothing,controlling brightness from terminal doesn't work)

To cut a long story short I have tried many solutions documented here, and the one shown here.

The one ray of hope is when I boot my computer with kernel 5.4.0-41 the brightness controller is there. When I use the default boot with kernel 5.4.0-42 the brightness controller is not there.

What I also notice is that when I run the command nividia-smi in the 42 kernel I get the following error message:

NVIDIA-SMI has failed because it couldn't communicate with the NVIDIA driver. 
Make sure that the latest NVIDIA driver is installed and running.

In 41 it is fine and returns valid results.

I believe that last time I fixed the disappearing brightness I forced a boot with an old kernel, but this was only temporary until the next update and the brightness disappeared again. Kernel -42 is the latest version from apt but only boots with low brightness and is hard to see in normal light conditions.

muru
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dan
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  • Thanks f or the formatting. But I'm still pulling my hair on this one. – dan Aug 05 '20 at 20:56
  • After more searching I've found that in the 41 kernel I have a folder: sys/class/backlight/nvidea_0 This is a symbolic link to what appears to control the brightness etc. In the non-working 42this link is missing. How do I make this link appear in kernel `42. Obi Wan? – dan Aug 06 '20 at 20:58
  • OK we're on Kernel .47 and still no fix. Can anyone help please. – dan Sep 07 '20 at 20:19

1 Answers1

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I have the same issue recently on my Asus ROG with GTX 1080 Ti. The recent kernel update is 5.4.0-51. I resolved the issue by re-installing the nvidia driver through ubuntu-drivers command line:

$ sudo ubuntu-drivers list ---> to see what drivers are available

$ sudo ubuntu-drivers install ---> to install the recommended driver

Hope this helps!

Ekawahyu Susilo
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