Bug 496954

Created attachment 176298 [details]
kscreen-doctor -o | ansifilter > hdr_disabled.txt

Some corrections to my previous comment since I'm not seeing any way edit:

> I've noticed that the brightness of my LG CX is noticably reduced and that adjustments made to the SDR Brightness slider have some but very little effect.    



> In order to verify that this is an issue with the display I temporarily booted back into Windows and confirmed that this is not the case so it seems as though it may possibly be related to how brightness of SDR content is being adjusted.

In order to verify that this is *NOT*  an issue with the display I temporarily booted back into Windows and confirmed that it's working correctly.



SUMMARY
I'm unsure as to whether this is somehow related to the following bug fix:
https://bugs.kde.org/show_bug.cgi?id=495557

I've noticed that my LG CX is noticeably more dim and that adjustments made to the SDR Brightness slider have some but very little effect.    

Normally, I have it set at 300 but even after increasing this value to 500 the screen is still extremely.

In order to verify that this is *NOT*  an issue with the display I temporarily booted back into Windows and confirmed that it's working correctly.

Disabling HDR has no effect and the screen is still extremely dim.

STEPS TO REPRODUCE
1.  Enable HDR *optional*
2.  Make adjustments to the SDR brightness slider 

Updated Steps:
The screen is still dim even when HDR is disabled.

OBSERVED RESULT
1.  The screen is very dim

EXPECTED RESULT
2.  The screen should not be dim when this slider has been set to 500

SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 41
KDE Plasma Version: 6.2.4
KDE Frameworks Version: 6.8.0
Qt Version: 6.8.0
Kernel Version: 6.11.10-300.fc41.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 7800X3D 8-Core Processor
Memory: 31.0 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 4090/PCIe/SSE2


ADDITIONAL INFORMATION
Possibly related: https://bugs.kde.org/show_bug.cgi?id=495557

Man is there really no way to edit comments?

Just disregard everything before "SUMMARY" in my previous comment.

SUMMARY
I'm unsure as to whether this is somehow related to the following bug fix:
https://bugs.kde.org/show_bug.cgi?id=495557

I've noticed that my LG CX is noticeably more dim and that adjustments made to the SDR Brightness slider have some but very little effect.    

Normally, I have it set at 300 but even after increasing this value to 500 the screen is still extremely.

In order to verify that this is *NOT*  an issue with the display I temporarily booted back into Windows and confirmed that it's working correctly.

Disabling HDR has no effect and the screen is still extremely dim.

STEPS TO REPRODUCE
1.  Enable HDR *optional*
2.  Make adjustments to the SDR brightness slider 

Updated Steps:
The screen is still dim even when HDR is disabled.

OBSERVED RESULT
1.  The screen is very dim

EXPECTED RESULT
2.  The screen should not be dim when this slider has been set to 500

SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 41
KDE Plasma Version: 6.2.4
KDE Frameworks Version: 6.8.0
Qt Version: 6.8.0
Kernel Version: 6.11.10-300.fc41.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 7800X3D 8-Core Processor
Memory: 31.0 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 4090/PCIe/SSE2


ADDITIONAL INFORMATION
Possibly related: https://bugs.kde.org/show_bug.cgi?id=495557

It looks like the PR which resolved the referenced bug report only changed the text output for kscreen so maybe it is unrelated.
There has definitely been some sort of regression by one of the recent updates though.

Additional Info:

While running some additional tests I noticed that screen only dims after completing the login step.

So when the OS first boots up into the SDDM the screen is NOT dim - it looks perfectly fine.
There's an HDR logo which briefly appears on the top right side of the screen indicating that it's receiving an HDR signal.   
After completing the login step the screen briefly turns off and on again but this time the screen is noticeably darker.

Hopefully that helps narrow down the possible cause of the issue.

Additional Info #2:
I also noticed that the screen appears to brighten up again when logging out.
So there's some text which displays on the screen indicating which services are being shutdown.
The screen is noticeably brighter when this happens.

Additional Info #2 (edit):
I also noticed that the screen appears to brighten up again when **restarting the OS.
So there's some text which displays on the screen indicating which services are being shutdown.
The screen is noticeably brighter when this happens.

Additional Info #3:

nvidia-settings:  version 565.57.01
  The NVIDIA Settings tool.

cat /etc/modprobe.d/nvidia.conf 

#https://download.nvidia.com/XFree86/Linux-x86_64/396.51/README/kms.html
options nvidia-drm modeset=1

#https://download.nvidia.com/XFree86/Linux-x86_64/510.39.01/README/gsp.html
options nvidia NVreg_EnableGpuFirmware=0

options nvidia_drm fbdev=1

> Brightness control: supported, set to 30%
You can move the brighntess slider in the system tray up to 100% to solve this.

The reason you have the brightness set to 30% is most likely bug 494722

*** This bug has been marked as a duplicate of bug 494722 ***

(In reply to Zamundaaa from comment #10)
> > Brightness control: supported, set to 30%
> You can move the brighntess slider in the system tray up to 100% to solve
> this.
> 
> The reason you have the brightness set to 30% is most likely bug 494722
> 
> *** This bug has been marked as a duplicate of bug 494722 ***

Wait...what?!  I didn't even know that this slider exists!  lol

Looks like this is the solution I was looking for but I'm a little surprised that this setting is not listed alongside SDR Brightness under Display Settings.

Anyway, Thanks for the help man.