1

I use an HP laptop with an AMD R7-5800U CPU and Ubuntu 18.04, and I can't adjust display brightness with kernel versions 5.4 or 5.10.3.

I also tried other solutions, including adjust the brightness in /sys/class/backlight, and in this path, there is a directory named as api_video0.

When I change the brightness from settings, the brightness in this path is changed while the screen brightness didn't change at all.

Improve this question
8
  • What is the model of the notebook? Some machines need to have an extra setting applied to a few files … – user1091774 Mar 6 at 5:02
  • hpstore.cn/hp-66-g4-14-35f14pc.html – Roger1219 Mar 6 at 6:23
  • it's the latest hp laptop in China with the latest AMD R7-5800U cpu. I found similar problems in previous 5600u cpu and it can be solved with linux kernel 5.4. – Roger1219 Mar 6 at 6:25
  • In other words - when changing brightness levels, the file /sys/class/backlight/acpi_video0/brightness changes the value written inside but the actual physical brightness does not change? – Pizza Mar 7 at 7:21
  • 1
    Is it possible that the new ubuntu system doesn't have proper driver for the new graphic card in new AMD 5800U cpu? And I search driver in AMD website. There is only a windows version driver. – Roger1219 Mar 8 at 14:14
0

I'm having the same problem with the same laptop. I tried 20.04, 20.10, but none of them works. Also the USB-C and hdmi doesn't work either.

Improve this answer
0

This is a problem common with Nvidia cards. If you do have an Nvidia video card, you are going to need to load the driver.

First of all do a uname -a, it will show something like 4.15.0-142-generic, not exactly that, but something like that in the output.

After that do sudo apt install linux-headers-4.15.0-142 linux-headers-4.15.0-142-generic. It's not going to be that exact version, but the numbers have to match whatever uname -a gave you.

Then you are going to add the graphics driver repository: sudo add-apt-repository ppa:graphics-drivers/ppa

Now you can check what driver is available: sudo ubuntu-drivers devices

It should display a list and some entry is going to say "recommended" next to it. So you can go ahead and install it. sudo ubuntu-drivers autoinstall

Make sure to reboot and you should be all set. All that said, I really do hope that somebody fixes the issue that linux-headers packages are never part of any dependencies even though you can't load the video drivers correctly without them. 16.04 had a huge problem where it lost its mind every time the kernel updated. Every time there was a kernel update, before rebooting had to remember to go in and manually install the correct header set. Otherwise pain was inevitable.

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.