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Fixing the Annoying Full Brightness Issue Under Linux and AMD Ryzen APUs

Daniel Hernandez

Posted đź•’

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TL; DR: What fixed the brightness issue was a mix between this and this StackOverflow post. Though I mainly attribue it to setting GRUB_CMDLINE_LINUX_DEFAULT="quiet splash amdgpu.backlight=0" in /etc/default/grub (make sure to sudo update-grub after changing this.) Though It doesn’t hurt to upgrade your kernel, especially if you’re in an earlier build of Ubuntu. You mileage may vary wildly.

Just Like Ten Years Ago

Oh GNU/Linux, I love you. Even when things don’t quite work, I enjoy the challenges. I remember trying to get my damn GPU to play nice with Ubuntu 12.04. Ten years later, things have gotten so much better. But as they say: the more things change, the more they stay the same.

New Laptop, Who’s This?

My last laptop is a used Lenovo Y-series that I bought off a very cautious dude from craigslist back in 2015. It was actually a titan of a laptop and it served me very well though all of these years.

The laptop is still very usable for most tasks (and part of me wonders just how much more use I can squeeze out of it). But, unfortunately, the model itself is almost 10 years old, has a tiny resolution, the GPU died a while ago, and the CPU is starting to choke with heavier loads. In short, I needed an upgrade.

I have been out of the laptop (and PC part) buying space since 2015, so I really didn’t know where to start; much less what to buy. So I did what anyone would do and submerged myself in Laptop YouTube for around two weeks.

Come to find out, laptop tech has gotten pretty good. While there’s a lot of options and critiques of said options, for me, almost anything made in the last 5 years was going to be a huge upgrade. So I set myself some parameters: powerful CPU, okayish display, a GPU, and relatively affordable. I settled for an HP Pavillion Gaming laptop—the model from MicroCenter specifically. It has an AMD 5600H, NVIDIA 1660 GPU, and 10809. I’ve had it for less than a week but it has been a great experience. Although I think that happiness mainly stems from the fact that I can actually see everything on screen. The magic of 1080p.

The Issue

As per tradition, I will now contradict myself. Everything has worked swimingly **under Windows. Thing is, I don’t use Windows unless I’m either gaming or making music. As of lately, I haven’t been doing much of either, so I spend my days in Linux.

Installing a distro on this laptop was pretty painless. Everything just works™ (even the secure boot stuff)…except for the brightness. No matter how many times I pressed F2/F3, the brightness was stuck at 100%. At first I thought it wasn’t playing nice with the NVIDIA card, since, in the past, most of my issues on Linux came as a result of NVIDIA drivers.

I tried installing the proprietary driver and nothing. I updated my kernel to the latest mainline, disabled the card altogether, still nothing. I even got rid of KDE Neon in favour of regular Ubuntu. Nothing! What gives?

The Solution

The solution to fix it in my case was changing the GRUB_CMDLINE_LINUX_DEFAULT setting in /etc/default/grub to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash amdgpu.backlight=0". Turns out it was the AMD APU.

It might not be as simple as that though, there’s a lot of conflicting info about the issue:

  • Some say it’s an outdated kernel issue
  • Others say it’s the NVIDIA driver
  • Perhaps it’s a Wayland issue?
  • A lot of claims say that it was already fixed

Regardless, I’m sure this will be a nonissue in the future. While this fixed the issue for me, your mileage may vary. Let me know if it helps.