Bug 495433

Summary: External Monitor as primary for laptop messes with external brightness control
Product: [Plasma] plasmashell Reporter: Abbhinav Jayaraman <jayabbhi>
Component: Power management & brightnessAssignee: Plasma Bugs List <plasma-bugs-null>
Status: RESOLVED WORKSFORME    
Severity: normal CC: jayabbhi, natalie_clarius, nate
Priority: NOR Keywords: multiscreen
Version First Reported In: 6.2.4   
Target Milestone: 1.0   
Platform: Fedora RPMs   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Abbhinav Jayaraman 2024-10-27 14:26:27 UTC 
SUMMARY:

When I use my external monitor as the primary display with my laptop, the brightness control feature on it will not work properly if the laptop is disconnected and reconnected. Not only will the actual brightness of the external monitor not be changed as expected, but the display's software color will change. It appears to the the gamma being changed, in an attempt to make the display dimmer since it doesn't have access to the hardware controls in this circumstance.

This becomes an issue whenever I need to take my laptop away from my monitor. If I reconnect the laptop and then reboot, the brightness control works as expected.

I tried messing with setting the powerdevil settings by setting POWERDEVIL_NO_DDCUTIL=1, and while I did successfully apply it, this just meant that I was stuck using the software brightness control that I don't want. How I go about completely disable any brightness manipulation on the external monitor, I do not know.

At least in my limited testing, this issue doesn't occur if I have my laptop's built-in display as the primary display.

STEPS TO REPRODUCE
1.  Use a laptop, and hook up a monitor that KDE Plasma 6.2 can manipulate the hardware's brightness.
2.  Set the external monitor to the primary display.
3.  disconnect and reconnect the laptop, or put the device to sleep while connected until the display goes to sleep after stating "No HDMI signal" then wake it up.

OBSERVED RESULT
The external display brightness control will manipulate the display color values to make the display dimmer, instead of manipulating the hardware's actual brightness

EXPECTED RESULT
The external monitor's actual hardware brightness should be manipulated in all situations.

SOFTWARE/OS VERSIONS
Operating System: Aurora-DX 40 (based on Fedora 40 Kinoite)
KDE Plasma Version: 6.2.0
KDE Frameworks Version: 6.7.0
Qt Version: 6.7.2
Kernel Version: 6.10.10-200.fc40.x86_64 (64-bit)
Graphics Platform: Wayland

ADDITIONAL INFORMATION
None at the moment, but I will try install the vanilla KDE Spin of Fedora and seeing if the issue persists.
Comment 1 Abbhinav Jayaraman 2024-10-27 18:04:34 UTC 
Full system information:

SOFTWARE/OS VERSIONS
Operating System: Aurora-DX 40 (based on Fedora 40 Kinoite)
KDE Plasma Version: 6.2.0
KDE Frameworks Version: 6.7.0
Qt Version: 6.7.2
Kernel Version: 6.10.10-200.fc40.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5800U with Radeon Graphics
Memory: 15.0 GiB of RAM
Graphics Processor: AMD Radeon Graphics
Manufacturer: Acer
Product Name: Swift SFX14-41G
System Version: V1.10
Comment 2 Abbhinav Jayaraman 2024-10-27 19:10:23 UTC 
I was able to replicate this issue on Fedora 40 KDE Spin as well.

Does the issue only occur on reboot, or sleep? Does the laptop have to be disconnected and then rebooted or slept to activate?


STEPS TO REPRODUCE
1.  Use a laptop, and hook up a monitor that KDE Plasma 6.2 can manipulate the hardware's brightness.
2.  Set the external monitor to the primary display.
3.  disconnect the laptop, reboot, then reconnect the laptop. This will make the software brightness control kick in, as opposed to the actual software brightness.

Operating System: Fedora Linux 40
KDE Plasma Version: 6.2.2
KDE Frameworks Version: 6.7.0
Qt Version: 6.7.2
Kernel Version: 6.11.4-201.fc40.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5800U with Radeon Graphics
Memory: 15.0 GiB of RAM
Graphics Processor: AMD Radeon Graphics
Manufacturer: Acer
Product Name: Swift SFX14-41G
System Version: V1.10
Comment 3 Abbhinav Jayaraman 2024-10-27 19:11:24 UTC 
ignore the (In reply to Abbhinav Jayaraman from comment #2)
> I was able to replicate this issue on Fedora 40 KDE Spin as well.
> 
> Does the issue only occur on reboot, or sleep? Does the laptop have to be
> disconnected and then rebooted or slept to activate?
> 
> 
> STEPS TO REPRODUCE
> 1.  Use a laptop, and hook up a monitor that KDE Plasma 6.2 can manipulate
> the hardware's brightness.
> 2.  Set the external monitor to the primary display.
> 3.  disconnect the laptop, reboot, then reconnect the laptop. This will make
> the software brightness control kick in, as opposed to the actual software
> brightness.
> 
> Operating System: Fedora Linux 40
> KDE Plasma Version: 6.2.2
> KDE Frameworks Version: 6.7.0
> Qt Version: 6.7.2
> Kernel Version: 6.11.4-201.fc40.x86_64 (64-bit)
> Graphics Platform: Wayland
> Processors: 16 × AMD Ryzen 7 5800U with Radeon Graphics
> Memory: 15.0 GiB of RAM
> Graphics Processor: AMD Radeon Graphics
> Manufacturer: Acer
> Product Name: Swift SFX14-41G
> System Version: V1.10

ignore the question on the 2nd line of this comment. That was just for my own notes
Comment 4 Abbhinav Jayaraman 2024-10-27 19:38:07 UTC 
Additionally, once the external monitor is in this "software brightness" mode, the only way to fix it is to reboot the device with the display attached. 

The issue doesn't seem to occur if I do not reboot the device when it is disconnected. This can be a little troublesome if I am rebooting to boot into windows when out and about.

The issue is respective of which display is the primary display.
Comment 5 Abbhinav Jayaraman 2024-10-27 19:38:31 UTC 
(In reply to Abbhinav Jayaraman from comment #4)
> Additionally, once the external monitor is in this "software brightness"
> mode, the only way to fix it is to reboot the device with the display
> attached. 
> 
> The issue doesn't seem to occur if I do not reboot the device when it is
> disconnected. This can be a little troublesome if I am rebooting to boot
> into windows when out and about.
> 
> The issue is respective of which display is the primary display.

IRRESPECTIVE, not respective.
Comment 6 Nate Graham 2025-05-20 18:14:17 UTC 
Are you able to reproduce this issue with Plasma 6.3.5 and ddcutil 2.2.0 or later?
Comment 7 Bug Janitor Service 2025-06-04 03:48:01 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 8 Bug Janitor Service 2025-06-19 03:48:09 UTC 
🐛🧹 This bug has been in NEEDSINFO status with no change for at least 30 days. Closing as RESOLVED WORKSFORME.