https://bugs.kde.org/show_bug.cgi?id=505556
Bug ID: 505556
Summary: Screen Brightness Incorrectly Retained from Battery
State After Rebooting on AC Power
Classification: Plasma
Product: plasmashell
Version First 6.3.5
Reported In:
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: Power management & brightness
Assignee: plasma-b...@kde.org
Reporter: hsanta...@gmail.com
Target Milestone: 1.0
Summary:
When a laptop is shut down while running on battery power, the screen
brightness level from the battery profile is incorrectly retained upon the next
boot, even if the device is connected to AC power before turning it on. The
system fails to apply the brightness settings configured for the "On AC Power"
profile at startup.
This issue is exacerbated by the inability to adjust screen brightness at the
SDDM login screen, a known issue tracked under bug report #417237. This leaves
the user with a potentially very dim and unusable screen until they have logged
in and can manually adjust the brightness.
Steps to Reproduce:
1. **Configure different brightness levels for battery and AC power:**
* Navigate to `System Settings > Power Management > Energy Saving`.
* On the **On Battery** tab, set a specific screen brightness, for example,
30%.
* On the **On AC Power** tab, set a different, higher brightness level, for
example, 80%.
2. **Operate and shut down on battery:**
* Disconnect the AC adapter and let the laptop run on battery power. The
screen brightness should adjust to the level set for the battery profile (e.g.,
30%).
* With the laptop still on battery power, perform a full shutdown.
3. **Boot up on AC power:**
* Connect the AC adapter to the laptop while it is powered off.
* Power on the laptop.
Observed Result:
The screen brightness at the SDDM login screen and after logging into the
Plasma session remains at the level that was active when the device was shut
down on battery power (e.g., 30%). The system does not apply the brightness
level configured for the "On AC Power" profile (e.g., 80%).
Expected Result:
When the laptop is booted while connected to AC power, the system should detect
the AC power state and apply the corresponding brightness setting (e.g., 80%)
at startup or, at the latest, upon reaching the login screen.
Additional Information:
This behavior appears to be closely related to Bug #497362, which has been
reported and marked as **RESOLVED FIXED** in Plasma 6.3. The underlying cause
was identified as PowerDevil failing to apply the correct profile at startup on
Wayland because the display output was not yet available when the profile
change was processed.
The inability to adjust brightness at the SDDM login screen (Bug #417237) makes
this primary issue more impactful, as users who had a low brightness setting on
battery are forced to navigate the login process with a very dim screen.
Software/OS Versions:
Operating System: Arch Linux
KDE Plasma Version: 6.3.5
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.1
Kernel Version: 6.12.33-1-lts (64-bit)
Graphics Platform: Wayland
Processors: 12 × Intel® Core™ i7-10750H CPU @ 2.60GHz
Memory: 15.4 GiB of RAM
Graphics Processor 1: NVIDIA GeForce GTX 1650
Graphics Processor 2: Intel® UHD Graphics
Manufacturer: LENOVO
Product Name: 82CG
System Version: IdeaPad Gaming 3 15IMH05
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