Bug 490535

Summary:	Brightness Slider sometimes not affecting every monitor
Product:	[Unmaintained] Powerdevil	Reporter:	jandominiksonnenwald
Component:	general	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	hein, jandominiksonnenwald, jpetso, me, natalie_clarius, nate
Priority:	NOR
Version First Reported In:	6.1.3
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description jandominiksonnenwald 2024-07-20 05:07:58 UTC

SUMMARY

I am using a dual monitor setup. Sometimes after restarting my PC, the Display Brightness slider from the Brightness and Color widget does not affect both screens.
For example, right now it only adjust the brightness from my second monitor and not my first.


STEPS TO REPRODUCE
I have not yet been able to accurately reproduce the issue. I will update this report when I have been able to do so. 
Sometimes a restart seemingly fixed the issue.

OBSERVED RESULT
Only 1 monitor's brightness gets adjusted.

EXPECTED RESULT
Both monitor's brightness should be adjustable with the slider.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux x86_64
Linux Kernel: Linux 6.6.40-1-lts
KDE Plasma Version: 6.1.3
KDE Frameworks Version: 6.4.0
Qt Version: 6.7.2

ADDITIONAL INFORMATION
I am using proprietary nvidia drivers:
- nvidia-lts 555.58.02-5
GPU:
- NVIDIA GeForce GTX 1080
My monitors:
- (ZOWIE XL LCD): 1920x1080 @ 144Hz [MAIN MONITOR]
- (ZOWIE RL LCD): 1920x1080 @ 60Hz [SECOND MONITOR]

Comment 1 Nate Graham 2024-07-27 03:40:04 UTC

Multi-screen brightness control is a bit underdeveloped in Plasma 6.1. We're hoping to have it hugely improved for 6.2.

Jakob, is there an existing bug report we could mark this as a duplicate of?

Comment 2 Jakob Petsovits 2024-07-28 14:49:21 UTC

(In reply to Nate Graham from comment #1)
> Jakob, is there an existing bug report we could mark this as a duplicate of?

I'm going to go out on a limb and hypothesize that this is one of the monitors not being detected via DDC/CI, in other words Bug 482713. We can't confirm that with the data at hand, though.

Jan, when this happens again, could you check and paste the output of `ddcutil detect`? Or enable verbose logging in PowerDevil as per PowerDevil README (https://invent.kde.org/plasma/powerdevil/-/blob/master/README.md) and then see what subsequent logs are showing for DDC display detection messages, e.g. (instead of 2 displays)

> [DDCutilDetector]: 1 display(s) were detected

Comment 3 jandominiksonnenwald 2024-07-29 06:18:55 UTC

(In reply to Jakob Petsovits from comment #2)
> (In reply to Nate Graham from comment #1)
> > Jakob, is there an existing bug report we could mark this as a duplicate of?
> 
> I'm going to go out on a limb and hypothesize that this is one of the
> monitors not being detected via DDC/CI, in other words Bug 482713. We can't
> confirm that with the data at hand, though.
> 
> Jan, when this happens again, could you check and paste the output of
> `ddcutil detect`? Or enable verbose logging in PowerDevil as per PowerDevil
> README (https://invent.kde.org/plasma/powerdevil/-/blob/master/README.md)
> and then see what subsequent logs are showing for DDC display detection
> messages, e.g. (instead of 2 displays)
> 
> > [DDCutilDetector]: 1 display(s) were detected

I will do that and post the output here. Thanks for the reply

Comment 4 Bug Janitor Service 2024-08-13 03:46:46 UTC

🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

Thank you for helping us make KDE software even better for everyone!

Comment 5 Bug Janitor Service 2024-08-28 03:47:45 UTC

🐛🧹 This bug has been in NEEDSINFO status with no change for at least 30 days. Closing as RESOLVED WORKSFORME.