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Brightness - ACPI or Xrandr - Which is good?
Posted: 06 Feb 2022, 09:30
by Testuser
Hi Team,
Just one query.
Regarding brightness control.
On Internet I found the difference but not sure.
ACPI - Hardware based brightness control - so power consumption is reduced.
Xrandr - Software based. Might not reduce power consumption.
Please advise with your thoughts.

Brightness - ACPI or Xrandr - Which is good?
Posted: 15 Feb 2022, 03:23
by Rava
Testuser wrote: ↑06 Feb 2022, 09:30
ACPI - Hardware based brightness control - so power consumption is reduced.
Xrandr - Software based. Might not reduce power consumption.
With the internal notebook's or sub-notebook's display I either use the XFCE system tray slider (but I have no clue what XFCE uses in the background), or a xrandr based script.
At least all external monitors I know and use only the monitor's own brightness control works.
Testuser wrote: ↑06 Feb 2022, 09:30
power consumption is reduced.
[…] Might not reduce power consumption.
Would be good to get exact findings on that. Does anyone know an article on the issue?
Brightness - ACPI or Xrandr - Which is good?
Posted: 27 Feb 2022, 10:56
by Testuser
Hi Rava,
Here is what I found.
https://wiki.archlinux.org/title/backlight.
For me xbacklight not workiing in Desktop, only working in laptop.
Xrandr - working on both desktops and laptop, So I beleive it is software based brightness control ( not actually reducing the brightness, this increases the blackness on the display - this is what I read in one of the forum in internet, now not able to find that link).
Anyway, I have posted a simple bright changer app for laptops using xbacklight and acpi.
This one uses yad program included in the package.
