Bug 485437

Summary:	Powerdevil restricts the minimum monitor brightness to 1%, causing it to be unable to reach the lowest possible brightness
Product:	[Plasma] Powerdevil	Reporter:	zvova7890
Component:	general	Assignee:	Plasma Bugs List <plasma-bugs>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	kde, me, natalie_clarius, nate
Priority:	NOR
Version:	6.0.3
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description zvova7890 2024-04-12 14:24:12 UTC

SUMMARY
This was introduced in KDE6. I know the Powerdevil team is trying to prevent some displays from turning off completely, but it also prevents other displays from reaching the minimum brightness. I think this is the wrong approach for Powerdevil because if the driver implements this, that's how it should work. Looking at the experience on MacOS, they allow the brightness to be fully turned off. My display doesn't fully turn off the brightness when its value is set to zero, and with the 1% restriction, I can't achieve the minimum brightness on my computer, which is bad for nighttime work.

Comment 1 Kai Uwe Broulik 2024-04-12 18:08:41 UTC

You can still use the brightness keys to go to 0%?

Comment 2 Nate Graham 2024-04-12 18:41:00 UTC

As you've found, this is intentional. How much of a difference is there between 1% and 2% with your hardware? Is it really noticeable enough to make a difference?

Comment 3 zvova7890 2024-04-12 20:12:51 UTC

>> You can still use the brightness keys to go to 0%?
No, I can't. Currently I'm using patched powerdevil to get minimal brightness. 

>> Is it really noticeable enough to make a difference?
Yes, otherwise I wouldn't be doing this report. Also, some monitors already have a minimum value that is not entirely acceptable, and it’s not good to aggravate this further with software.

Comment 4 Nate Graham 2024-04-15 14:19:29 UTC

Well, we're in an awkward situation here where we don't have any ideal choices:

1. Always let the brightness go to 0% - with many devices and drivers, this turns off the backlight entirely, which is not useful. We get bug reports.

2. Always stop at 1% - for devices where the minimum brightness value doesn't turn off the backlight, the lowest brightness level is locked out. We get bug reports.

3. Usually stop at 1%, but allow going down to 0% with some kind of less obvious UI - inconsistency that people don't understand. We get bug reports.

4. Make it user-configurable: amounts to a workaround for hardware/driver bugs that 99.9% of users will not understand or care about; increasing complexity in the process. We would probably stop getting bug reports, but at the cost of a more cluttered UI unless we hid the setting somewhere deep in the powerdevil KCM, in which case people who could benefit from it might not find it and we'd get bug reports anyway.

5. Go out there and fix all hardware and GPU drivers to never turn off the backlight at minimum brightness - infeasible as we lack the resources and technical know-how.


Maybe #4 is the last-bad choice, and in fact Natalie submitted a merge request to do this in https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/4117. Let's follow up there.

*** This bug has been marked as a duplicate of bug 483490 ***