[Solved] Laptop Monitor Brightness - Power Manager - Not Adjusting

lmat · 2017-11-21 01:43:40

I have an arch linux system with xfce 4.12, xfce4-power-manager 1.6.0. I'm using a Dell Precision 7710 (17.3" screen). When I click the power manager icon, the window shows up with a slider for brightness. The slider is all the way to the right (maximum brightness). When I slide it, nothing changes.

My monitor is perpetually quite dim. When booting, GRUB is bright, but some time after GRUB goes away, the brightness noticeably decreases and can't be coaxed back to brightness.

When I run xfce4-power-manager --debug --no-daemon; and press the brightness-increase key on my keyboard, there are messages saying that the level is 255. When I press the brightness-decrease key, the number goes down to 230, 211, etc., and the number will go back up when I press brightness-increase. The brightness never actually changes, though. I have another Dell Precision (4450 maybe?) which works just fine.

Any suggestions about how I should go about debugging this? Thanks!

Last edited by lmat (2017-11-23 03:34:05)

ToZ · 2017-11-21 02:00:15

Hello and welcome.

What video card(s) do you have?

How many brightness interfaces do you have?

ls /sys/class/backlight

lmat · 2017-11-21 11:48:56

lmat@zwingli~$ ls -l !$
ls -l /sys/class/backlight/
total 0
lrwxrwxrwx  1 root root 0 Nov 21 06:43 intel_backlight -> ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/
lrwxrwxrwx  1 root root 0 Nov 21 06:43 radeon_bl1 -> ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card1/card1-eDP-2/radeon_bl1/
lawsa@zwingli~$ lspci | grep -i vga
3:00:02.0 VGA compatible controller: Intel Corporation HD Graphics 530 (rev 06)
17:01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Venus XTX [Radeon HD 8890M / R9 M275X/M375X] (rev 83)
lmat@zwingli~$

ToZ · 2017-11-22 01:50:39

Look at the values inside the files

- /sys/class/backlight/intel_backlight/brightness
- /sys/class/backlight/intel_backlight/max_brightness

- /sys/class/backlight/radeon_bl1/brightness
- /sys/class/backlight/radeon_bl1/max_brightness

Then echo a value between 0 and the contents of max_brightness to the brightness file ala:

echo XX | sudo tee /sys/class/backlight/INTERFACE/brightness

...where XX is a value between 0 and that interface's max_brightness file and INTERFACE is either intel_backlight or radeon_bl1.

See if manually changing the brightness in either of those interfaces changes the actual computer brightness. If not, you're issue is with your video card's handling of brightness and not within Xfce.

lmat · 2017-11-22 02:27:14

First things first: you da man. Free software is built and carried on backs like yours. Thank you immensely!

Manipulating the radeon API didn't do anything, but the intel set worked. This is surprising to me because everything I see from my computer suggests I have a radeon card. I'm guessing that xfce is using the radeon API, too, and that's why it's not working. I thought it may have worked a LONG time ago...maybe when I first installed the power manager plugin?

Any advice getting xfce to use the other api? (I'm sure I'm over-simplifying!)

Thanks again.

ToZ · 2017-11-22 03:32:20

There was this commit that was made post 1.6.0 that has not been officially released yet that might fix the problem for you. Unfortunately, Arch doesn't have a git version package of xfce4-power-manager in the AUR that you can easily install, so if you want to try it you'll need to build it from source.

It looks like you have a a hybrid ati/intel setup. I don't have any experience with these kinds of setups, but perhaps there is an option there to set the intel as the main interface (there is info and instructions there on how to disable the discrete ATI card as an option).

Also have a look through the backlight wiki. There is more info there about kernel parameters you can try and an inotify script that you can use to change the values on one interface when the other interface changes.

lmat · 2017-11-22 12:02:54

That was committed in may of 2016? What is the release cycle?

Thank you very much. How do I mark this as solved?

ToZ · 2017-11-23 01:46:06

lmat wrote:

That was committed in may of 2016? What is the release cycle?

Complicated.

Xfce is almost complete with it's GTK3 migration so there have been a lot of development releases and non-releases while functionality is tested. The last "official" release of the power manager was 20 months ago. However, many distros will cherry-pick post-1.6.0 commits to add to their released packages. The next 4.14 Xfce release, which will include all new versions of all the associated packages, is pending. Still some work to do and much testing.

Thank you very much. How do I mark this as solved?

Just edit your original post and pre-pend "[SOLVED]" to the title.

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#1 2017-11-21 01:43:40

[Solved] Laptop Monitor Brightness - Power Manager - Not Adjusting

#2 2017-11-21 02:00:15

Re: [Solved] Laptop Monitor Brightness - Power Manager - Not Adjusting

#3 2017-11-21 11:48:56

Re: [Solved] Laptop Monitor Brightness - Power Manager - Not Adjusting

#4 2017-11-22 01:50:39

Re: [Solved] Laptop Monitor Brightness - Power Manager - Not Adjusting

#5 2017-11-22 02:27:14

Re: [Solved] Laptop Monitor Brightness - Power Manager - Not Adjusting

#6 2017-11-22 03:32:20

Re: [Solved] Laptop Monitor Brightness - Power Manager - Not Adjusting

#7 2017-11-22 12:02:54

Re: [Solved] Laptop Monitor Brightness - Power Manager - Not Adjusting

#8 2017-11-23 01:46:06

Re: [Solved] Laptop Monitor Brightness - Power Manager - Not Adjusting

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