this post was submitted on 16 Mar 2026
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Strange brightness bug on Debian/Ubuntu/Mint (lemmy.org)
submitted 22 hours ago* (last edited 19 hours ago) by Cekan14@lemmy.org to c/linux@lemmy.ml
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Good day, folks!

I hope you won’t mind helping me with some troubleshooting.

I currently run Debian 13 Stable with KDE Plasma (Wayland). I have an Asus laptop with an AMD Vega integrated GPU and an Nvidia 2060 Mobile dedicated GPU.

Error shown in the attached GIF. Had to shorten it, but the flickering repeats non stop.

~~First of all, I’m sorry I can’t provide you with a video; I tried attaching it to the post but won’t let me attach any other than photos.~~

This issue shows up at random: when closing the lid and thus leaving the system suspended, I later open it up to continue using it and the bug manifests. The screen brightness ‘flashes’ and increasing or decreasing brightness manually doesn’t solve it. Most times, it suffices with closing the lid and opening it up again for the issue to disappear and, for the times it doesn’t work, a reboot is needed.

Now, one might think that this is an Nvidia driver-related issue. While I currently haven’t installed the proprietary driver and, thus, I suppose the open source Nouveau driver is in place instead, what makes me discard that possibility is that, prior to Debian, I tried Ubuntu and Mint (based on the former), in both of which I did install such Nvidia drivers, and the exact same issue occurred.

As far as I know, the AMD drivers are included with the Linux kernel, so that shouldn’t be the issue (?)

It doesn’t seem to be a Wayland issue either, since I’ve tried both X11 and Wayland, the issue showing up on both.

Finally, if it’s worth mentioning, this issue didn’t happen back on Windows. Not that I am planning on going back, rest assured.

I am thus out of ideas as to what might be causing this or what else try to do. I appreciate any clues you could provide me with.

Thank you in advance :)

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[–] just_another_person@lemmy.world 5 points 20 hours ago (2 children)

Sounds like this is an older laptop perhaps? Probably the voltage regulator for the display panel not coming back on cleanly.

Try this:

  1. Trigger the issue
  2. Once the issue starts, turn your brightness ALL the way up and see if it stops
  3. If it does, then lower it back down to whatever level seems appropriate

See if that does anything.

[–] Cekan14@lemmy.org 1 points 12 hours ago (1 children)

Hi, again!

So, first of all, this is a refurbished laptop I bought back at 2021 (probably a model from 2019 or 2020, if that's considered old enough)

Now, I have forced the laptop to trigger the issue by repeatedly closing and opening right now and I am writing as the screen flashes at this moment:

Having tried increasing brightness up to 100 %, the issue persists. Additionally, lowering all the way down to 0 % doesn't solve it either.

Thank you, though; I'll keep looking for clues.

[–] just_another_person@lemmy.world 1 points 12 hours ago

Look up the model of the laptop, and try to find a "display voltage regulator". Sometimes they sell them a setnfor cheap.

This isn't a software or OS issue though.

[–] Cekan14@lemmy.org 1 points 20 hours ago

Thanks; will try when I get home

[–] brickfrog@lemmy.dbzer0.com 1 points 17 hours ago* (last edited 17 hours ago) (1 children)

Some ideas:

  • You could try changing some of the power save settings when you close your laptop lid to see if it helps. I have a spare laptop that used to get stuck with a scrambled display when going into suspend then waking up, it ended up being easier just to disable suspend altogether.. I think for whatever reason Hibernate actually behaved better than suspend in my specific case. Granted its been a while since I retested all that against the current Debian version. Take a look through https://wiki.debian.org/Suspend for some ideas

  • It's possible Nouveau is still a bit buggy with suspend/resume, plus maybe when paired with hybrid/optimus graphics mode? I don't have a solid solution for that but it could be worth experimenting with the regular Nvidia driver, Debian has a pretty detailed how-to on setting it up https://wiki.debian.org/NvidiaGraphicsDrivers .. in particular take a look at enabling NVreg_PreserveVideoMemoryAllocations (see https://wiki.debian.org/NvidiaGraphicsDrivers#Wayland_configuration) to help with suspend/resume, maybe the driver along with that setting will do the trick? The big caveat here is that same Debian page mentions

Warning: enabling NVreg_PreserveVideoMemoryAllocations will cause the driver to malfunction on laptops with Optimus hybrid graphics.

and it does sound like you have some sort of hybrid graphics setup, so I can't say if enabling it would be helpful or very bad in your case. :/

  • I wonder if the issue is manifesting due to the hybrid graphics? I haven't played around with one of those type of configurations but maybe you could go into your laptop's BIOS and try disabling one of them so you're always using the Nvidia graphics, or the AMD graphics?

  • Speaking of BIOS, kind of a longshot but you could double-check if your BIOS is up-to-date. Power saving issues could just be due to buggy firmware particularly with laptops. But sometimes you'll just have to look for workarounds if the firmware itself quite right and the laptop vendor never fixes it.

[–] Cekan14@lemmy.org 1 points 10 hours ago

Hi, and thank you for your detailed reply. You brought up a few interesting points I hadn't considered.

While I haven't had time today to look into all your suggestions, I've focused on the last two related to the BIOS:

First of all, aparently, my BIOS does not have, or at least I have not found, an option to disable either GPU. Perhaps I'm missing something but, going to the advanced settings, this is all that shows up:

Secondly, I have run the "inxi -Faz" command and it tells me my BIOS version is from January 2021. According to my laptop's manufacturer website, the latest BIOS driver available for my system dates from March 2021, so I'm not sure it would make a great difference, but I will still look into how it could be updated without using Windows (which I no longer have lol).

As soon as I have the time, I'll take a look at your other suggested points as well.

Thank you and have a nice evening!

[–] memphis@sopuli.xyz 2 points 20 hours ago (1 children)

You mentioned trying Plasma on X11 and Wayland. Have you tried a different desktop environment? Just to rule out Plasma. You could temporarily install something small like dwm or Sway just for testing.

[–] Cekan14@lemmy.org 1 points 19 hours ago* (last edited 19 hours ago) (1 children)

Yes, I used Ubuntu's GNOME and Mint's Cinammon when trying those distros, but the issue was also present.

I've gotta ask, what is dwm / Sway?

[–] memphis@sopuli.xyz 2 points 17 hours ago (1 children)

They are just the first small and standalone window managers for X11 and Wayland respectively that came to mind for me. Not necessarily relevant

[–] Cekan14@lemmy.org 2 points 17 hours ago

Thank you; I'll look into it, though, out of curiosity

[–] atomicStan@programming.dev 2 points 20 hours ago* (last edited 20 hours ago) (1 children)

First of all, I’m sorry I can’t provide you with a video; I tried attaching it to the post but won’t let me attach any other than photos.

Gifs work. There are some pointers over here.

[–] Cekan14@lemmy.org 2 points 20 hours ago

Thank you!