Bug 486072 - Display brightness slider in applet available for HDMI/DP monitor, but has no effect
Summary: Display brightness slider in applet available for HDMI/DP monitor, but has no...
Status: REPORTED
Alias: None
Product: plasmashell
Classification: Plasma
Component: Power management & brightness (show other bugs)
Version: 6.2.4
Platform: Fedora RPMs Linux
: NOR normal
Target Milestone: 1.0
Assignee: Plasma Bugs List
URL:
Keywords:
: 489397 (view as bug list)
Depends on:
Blocks:
 
Reported: 2024-04-24 13:30 UTC by postix
Modified: 2025-03-06 20:50 UTC (History)
5 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
ddcutil interrogate output (136.48 KB, text/plain)
2024-04-25 12:42 UTC, postix
Details

Note You need to log in before you can comment on or make changes to this bug.
Description postix 2024-04-24 13:30:11 UTC
SUMMARY

Display brightness slider in applet available but has no effect. 
Journalctl logs when moving the slider:

```
org_kde_powerdevil dh=DISPLAY_Handle[i2c-0: fd=24], Replacing adjusted sleep multiplier 0,10 with 1.00 for SE_POST_WRITE or SE_POST_SAVE_SETTINGS.
```

The monitor is a iiyama ProLite XUB2792HSU


SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 40
KDE Plasma Version: 6.0.3
KDE Frameworks Version: 6.0.0
Qt Version: 6.6.2
Kernel Version: 6.8.7-300.fc40.x86_64 (64-bit)
Graphics Platform: Wayland
Comment 1 postix 2024-04-25 12:42:58 UTC
Created attachment 168894 [details]
ddcutil interrogate output

Please find the `ddcutil interrogate` output attached for further investigation. The display is currently connected via an HDMI cable.
Unfortunately in the moment I don't have a DP cable at hand for testing.
Comment 2 Nate Graham 2024-07-27 12:53:24 UTC
Does it still happen in Plasma 6.1.3 or later?
Comment 3 postix 2024-07-27 13:49:00 UTC
Can check in a few weeks again.
Comment 4 postix 2024-07-28 13:45:06 UTC
Logged in remotely with Wireguard + krdc, upgraded, rebooted and tested: Nope, still broken unfortunately!
Comment 5 Nate Graham 2024-07-29 17:51:46 UTC
When you adjust the slider and it does nothing, does `kscreen-doctor -o` say that the monitor's brightness is at the level you specified?
Comment 6 Bug Janitor Service 2024-08-13 03:46:44 UTC Comment hidden (spam)
Comment 7 postix 2024-08-17 19:55:41 UTC
There's no info about any brightness:
```
kscreen-doctor -o
Output: 1 HDMI-A-1
        enabled
        connected
        priority 1
        HDMI
        Modes:  0:1920x1080@60*!  1:1920x1080@75  2:1920x1080@60  3:1920x1080@60  4:1920x1080@50  5:1600x1200@60  6:1680x1050@60  7:1280x1024@75  8:1280x1024@60  9:1440x900@75  10:1440x900@60  11:1280x960@60  12:1280x800@60  13:1152x864@75  14:1280x720@60  15:1280x720@60  16:1280x720@60  17:1280x720@50  18:1152x720@60  19:1024x768@75  20:1024x768@60  21:832x624@75  22:800x600@75  23:800x600@60  24:720x576@50  25:720x576@50  26:720x480@60  27:720x480@60  28:720x480@60  29:720x480@60  30:640x480@75  31:640x480@60  32:640x480@60  33:640x480@60  34:720x400@70  35:1280x1024@60  36:1024x768@60  37:1280x800@60  38:1920x1080@60  39:1600x900@60  40:1368x768@60  41:1280x720@60
        Geometry: 0,0 1920x1080
        Scale: 1
        Rotation: 1
        Overscan: 0
        Vrr: incapable
        RgbRange: unknown
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
        Color profile source: sRGB
```

journalctl 
```
org_kde_powerdevil[6220]: dh=Display_Handle[i2c-0: fd=31], Replacing adjusted sleep multiplier 0,50 with 1.00 for SE_POST_WRITE or SE_POST_SAVE_SETTINGS
```
Comment 8 Nate Graham 2024-08-21 15:25:03 UTC
Ok, so KWin correctly thinks you don't have monitor brightness control, but Powerdevil disagrees.
Comment 9 postix 2024-10-31 17:07:12 UTC
The issue remains now on Fedora 41 with Plasma 6.2.2, but there's now no longer any log output when moving the slider, neither in journalctl nor in dmesg. 

Could it be detected that brightness changing doesn't work with powerdevil and fallback to a software overlay?
If not, could an option be added? The broken state right now, is a bit unfortunate. :)
Comment 10 postix 2024-10-31 17:08:44 UTC
Additionally resolving bug #495248 would also enhance the UX in this regard.
Comment 11 postix 2024-11-13 12:03:01 UTC
I've tested it again with

Operating System: Fedora Linux 41
KDE Plasma Version: 6.2.3
KDE Frameworks Version: 6.8.0
Qt Version: 6.8.0
Kernel Version: 6.11.7-300.fc41.x86_64 (64-bit)
Graphics Platform: Wayland

now with both HDMI and DP cable there's no brightness change but on slider release it logs
```
rg_kde_powerdevil[2978]: dh=Display_Handle[i2c-3: fd=32], Replacing adjusted sleep multiplier 0,10 with 1.00 for SE_POST_WRITE or SE_POST_SAVE_SETTINGS
```
Comment 12 TraceyC 2025-03-06 20:48:54 UTC
*** Bug 489397 has been marked as a duplicate of this bug. ***