Bug 418502

Summary:	better handling of external monitor brightness.
Product:	[Unmaintained] Powerdevil	Reporter:	Marcos Dione <mdione>
Component:	general	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED FIXED
Severity:	wishlist	CC:	daniel-other+kdebug, jpetso, natalie_clarius, nate, postix
Priority:	NOR
Version First Reported In:	5.16.5
Target Milestone:	---
Platform:	Kubuntu
OS:	Linux
See Also:	https://bugs.kde.org/show_bug.cgi?id=470107
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Marcos Dione 2020-03-05 17:01:19 UTC

To start with, I'm not sure this is the right component. Please advise me which one if not.

SUMMARY
The lightning in my office varies a lot with weather and time. I also have the redshift control plasma plugin on. The HW setup is: one notebook with an external screen, so two screens in total. I have a couple of issues with this setup.

* The brightness up/down keystrokes (Fn+F11/F12) only handle the notebook's screen brightness, but not the external screen. I do this everitime I feel my eyes are straining to handle the low or high brightness independently of the time of the day.

* I can change the external screen's brightness with`xrandr`, but if redshift is enabled, it resets it to the brightness it thinks it should have based on the config and time of the day, only on the external screen (the laptop's abides my wishes).

STEPS TO REPRODUCE
1. have a laptop (dell precision 5220)
2. attach external screen (dell 22", not sure the model).
3. change brightness with keyboard (external screen does not change).
4. enable redshift control.
5. use `xrandr` to change external screen's brightness (`xrandr --output HDMI-1 --brightness 0.7`; brightness changes, but then redshift takes over and resets)

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Kubuntu 19.10
KDE Plasma Version: 5.62.0-0ubuntu2
KDE Frameworks Version: 5.62.0-0ubuntu1
Qt Version: 5.12.4-1

Comment 1 Daniel 2020-08-21 18:44:15 UTC

Can confirm this. I think there are a couple of separate issues:

1. The screenbrightness of external screens isn't affected when changing the screenbrightness using the applet or the hardware keys. (wishlist)

2. When setting the screenbrightness using xrandr, while redshift/Night color is active: The screen gets darker, but the color temperature is totally off (too much blue, when it should be more red) (bug)

3. Redshift reset the brightness which was set by xrandr after about 10-30 seconds. (bug)

Marcos, please note, that KCM_Nightcolor doesn't change the screen brightness yet AFAIK, but the color tone (see #413165)

Comment 2 Marcos Dione 2021-09-13 19:05:12 UTC

> but the color temperature is totally off (too much blue...)

I think what happens here is that redshift gets disabled.

> that KCM_Nightcolor doesn't change the screen brightness yet AFAIK, but the color tone

Then this becomes a dupe of #413165?

Comment 3 Marcos Dione 2021-10-21 19:39:43 UTC

I have to note that redshift is able to do it. I'm currently running

redshift -v -b 1:.65 -l 43.5:7.1

and it's handling both monitors just fine.

Comment 4 Marcos Dione 2023-02-02 10:00:46 UTC

I just noticed that I can set the external monitor brightness with ddccontrol and redshift does not seem to impose its own wishes. In fact, seemingly nor on the notebook's monitor, so I guess this is fixed now?

Comment 5 Jakob Petsovits 2023-12-03 05:39:19 UTC

Seems fixed for the original reporter. Daniel from Comment 1, could you retest with a more recent Plasma given that you were able to confirm earlier? Otherwise I think it seems fair to let the automatic bug janitor close this bug if no more inconveniences are reported after a while. (Hopefully the NEEDSINFO/FIXED combo will do the right thing.)

Comment 6 Daniel 2023-12-04 21:29:45 UTC

I agree, the original bug seems fixed (aka changing the "fake" brightness with xrandr is blocked). However, brightness handling could still be improved by supporting setting the brightness of external screens using DDC like it is currently possible for laptop screens with the widget (this is what is linked in the "see also" I think)