I am using Tumbleweed KDE ( Tumbleweed 20250916 / KDE Plasma Version: 6.4.5 / KDE Frameworks Version: 6.18.0 / Qt Version: 6.9.2 / Kernel Version: 6.16.7-1-default (64-bit) / Graphics Platform: X11), but from recently after some updates, the minimum screen brightness is visibly higher than in the past.
By default, the brightness is set to 5% and in previous versions when I set it to 0% the brightness was being reduced.
Then in some later versions the lowest brightnes was not 0%, but 1% instead, but nevertheless in both cases the screen was visibly darker than 5% brightness.
Currently 5% is too bright and reducing it to below 5% makes no difference.
It would be more convenient if the brightness can again be reduced below 5%.
Thank you for your consideration and let me know if you need further information!
It may well depend on your monitor make/model/age.
0% screen brightness in the settings does not really mean a black screen.
The difference between 0% and 5% is clearly visible here on all hardware. With 0% it is impossible to work anymore.
You may need to check your monitor settings as these contain often additional modes/settings (landscape, race, cinema, RTS/RPG, FPS, sRGB, MOBA, and many more modes) which can not be acessed through any external DE applet or slider. Also check if you can reproduce your issue with a fresh user profile.
Also some basic information about your hardware would be good: inxi -GSaz
There was a user on our Matrix platform, who reported the same issue, also reported later that they did not have the issue on Plasma6 with Wayland. Given that X11 is going to be phased out, I would strongly suggest to make the switch to Wayland and see if the issue persists.
On my laptop I have to use the kernel command-line parameter
acpi_backlight=video
to get proper control of my screen brightness.
This parameter can be set to different values
acpi_backlight= [HW,ACPI]
{ vendor | video | native | none }
If set to vendor, prefer vendor-specific driver
(e.g. thinkpad_acpi, sony_acpi, etc.) instead
of the ACPI video.ko driver.
If set to video, use the ACPI video.ko driver.
If set to native, use the device's native backlight mode.
If set to none, disable the ACPI backlight interface.
You will have to try if any is useful for you.
If you switch to Wayland you may loose the ability to share your clipboard with VMs (just in case you use VMs).
@susejunky it all depends on the GPU hardware, only way to see is looking at the journal to see what @backlight service is fighting (or failing) for control… My Leap 15.6 has an AMD GPU, I disable/mask the apci service in favor of the amd one…
hui sorry I forgot to mention that I use laptop, so there is no an external monitor to further adjust the settings.
@knurpht I switched to Wayland, but the result is the same.
@susejunky based on your reply with the help of ChatGPT I found out that AMD GPU is directly controlling the backlight. ls /sys/class/backlight/ returned amdgpu_bl1 only and I cannot go any darker using hardware backlight controls — the AMD GPU/firmware won’t let me, because currently it is at its lowest possible level at 1.
It is strange/unexplainable though, because until recently just by using the brightness slider in the system tray I could make the minimum brightness level lower than the current minimum level, as if the minimum built in AMD GPU brighntess level has increased.
Novertheless, thanks to you all for the replies! At least I know now there is nothing that can be done to further reduce the brightness, except using a software dimming.
For a better idea of your system and graphics details, please share the results from inxi -SGaz, and post the output as preformatted text (refer </> button in forum editor).