Bug 499240 - No brightness slider for external monitor if it’s plugged in after login
Summary: No brightness slider for external monitor if it’s plugged in after login
Status: RESOLVED UPSTREAM
Alias: None
Product: plasmashell
Classification: Plasma
Component: Power management & brightness (other bugs)
Version First Reported In: master
Platform: Other Linux
: NOR normal
Target Milestone: 1.0
Assignee: Plasma Bugs List
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-01-28 14:46 UTC by ariasuni
Modified: 2025-02-27 22:17 UTC (History)
3 users (show)

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Description ariasuni 2025-01-28 14:46:16 UTC 
SUMMARY
I don’t have a brightness slider if I plug the external monitor after login.
I experience the bug both with HDMI onto my usb-C dock, and with direct HDMI connection.
I didn’t try DisplayPort or another external screen.
Logging out and back in fixes the problem.

STEPS TO REPRODUCE
1. Log into Plasma
2. Plug an external monitor supported by `ddcutil`

OBSERVED RESULT
There’s no brightness slider for my external monitor.

EXPECTED RESULT
There’s a brightness slider for my monitor.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.2.5
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.1
Kernel Version: 6.12.10-zen1-1-zen (64-bit)
Graphics Platform: Wayland
Processors: 8 × AMD Ryzen 7 3700U with Radeon Vega Mobile Gfx
Memory: 13.5 Gio of RAM
Graphics Processor: AMD Radeon Vega 10 Graphics
Manufacturer: LENOVO
Product Name: 20NFCTO1WW
System Version: ThinkPad E595

ADDITIONAL INFORMATION
The screen is a Dell P2423D.
Comment 1 Nate Graham 2025-01-28 16:34:35 UTC 
Jakob, do you think this is the general case of Bug 482713, or something more specific?
Comment 2 Jakob Petsovits 2025-02-24 18:24:36 UTC 
ddcutil 2.2.0 is now released and available on Arch Linux, its display change detection was vastly improved compared to 2.1.4. Could you verify if this is still an issue for you after updating ddcutil to the latest version?
Comment 3 ariasuni 2025-02-27 22:17:24 UTC 
Indeed, it works well with ddcutil 2.2.0.