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#1 2022-02-03 19:06:09

mass_t
Member
Registered: 2015-04-21
Posts: 57

The backlight level is no longer adjustable

Broken brightness control in gnome 41.3 kernel 5.16.5 and zen-kernel 5.16.5, I remembered that in kernel 5.11 it was necessary to set the level manually in the file  /sys/class/backlight/amdgpu_bl1/actual_brightness
But now I dont have permission to write to this file.

# LANG=en_US.UTF-8 tee /sys/class/backlight/amdgpu_bl1/actual_brightness <<< 10
tee: /sys/class/backlight/amdgpu_bl1/actual_brightness: Permission denied
10

My hardware is 82B1 Lenovo Legion 5 15ARH05H with AMD Ryzen 7 4800H and GeForce RTX 2060 Mobile.

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#2 2022-02-03 19:24:00

mass_t
Member
Registered: 2015-04-21
Posts: 57

Re: The backlight level is no longer adjustable

Also, I'm using X11, not wayland.

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#3 2022-02-03 19:31:10

Head_on_a_Stick
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From: London
Registered: 2014-02-20
Posts: 7,680
Website

Re: The backlight level is no longer adjustable

See https://bbs.archlinux.org/viewtopic.php?id=260428

But it's probably best to use brightnessctl instead.

Before you post again be sure to read the "Backlight" page in the ArchWiki wink

EDIT: and if this is a kernel regression then follow https://wiki.archlinux.org/title/Bisect … s_with_Git and/or submit a bug report.

Last edited by Head_on_a_Stick (2022-02-03 19:33:43)

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#4 2022-02-03 19:39:29

mass_t
Member
Registered: 2015-04-21
Posts: 57

Re: The backlight level is no longer adjustable

Head_on_a_Stick wrote:

But it's probably best to use brightnessctl instead.

Thanks, that work

sudo brightnessctl -c backlight -d amdgpu_bl1 s 50

. But for me it's better to use standard control backlight in gnome smile

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#5 2022-02-03 20:07:06

Head_on_a_Stick
Member
From: London
Registered: 2014-02-20
Posts: 7,680
Website

Re: The backlight level is no longer adjustable

Did you try without sudo? This works for me:

$ brightnessctl  s 50

Did the GNOME backlight control work with previous kernel versions?

Did you read the "Backlight" wiki page?

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#6 2022-02-03 21:19:32

mass_t
Member
Registered: 2015-04-21
Posts: 57

Re: The backlight level is no longer adjustable

Head_on_a_Stick wrote:

Did you try without sudo? This works for me:

$ brightnessctl  s 50

Did the GNOME backlight control work with previous kernel versions?

Did you read the "Backlight" wiki page?

$ brightnessctl  s 50
Updated device 'nvidia_0':
Device 'nvidia_0' of class 'backlight':
	Current brightness: 50 (50%)
	Max brightness: 100

But this no affected. Need manualy set the device `brightnessctl -c backlight -d amdgpu_bl1 s 100` and this work, without root.

Yes, gnome control works with 5.15.3 or 5.15.4.
I have read the wiki. Sorry, but I do not quite understand what I was supposed to find there. The dimming issue on my laptop was fixed in the 5.11 kernel, everything has been working fine ever since and set up as it should. Today I upgraded the kernel and rebooted the system to make iptables work, found that the brightness control from gnome did not work.

Last edited by mass_t (2022-02-03 21:21:48)

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#7 2022-02-05 11:00:54

f_fouad
Member
Registered: 2017-09-08
Posts: 8

Re: The backlight level is no longer adjustable

I have the same Lenovo laptop but with different GPU GTX 1650Ti. It was working before in both kernels 5.16 and LTS 5.15. I had acpi_backlight=none set as kernel parameter just to remove some unnecessary log errors.

Tried KDE and it is working. I think it is related to gnome and nvidia and not the kernel. Probably, not using the right driver for backlight control. I have noticed the same new device nvidia_0 for brightness control which was absent before.

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#8 2022-02-05 11:16:52

f_fouad
Member
Registered: 2017-09-08
Posts: 8

Re: The backlight level is no longer adjustable

Actually, it is not working for KDE. It was before installing updates.

It is related to nvidia. I downgraded nvidia to 495 and backlight is working fine.

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#9 2022-02-05 15:54:12

mass_t
Member
Registered: 2015-04-21
Posts: 57

Re: The backlight level is no longer adjustable

f_fouad wrote:

Actually, it is not working for KDE. It was before installing updates.

It is related to nvidia. I downgraded nvidia to 495 and backlight is working fine.

What the packages you downgraded?

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#10 2022-02-06 12:11:33

f_fouad
Member
Registered: 2017-09-08
Posts: 8

Re: The backlight level is no longer adjustable

nvidia and nvidia-utils to the latest revision of 495 series. You should downgrade nvidia-lts also if you have LTS kernel installed.

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#11 2022-02-07 07:40:32

mass_t
Member
Registered: 2015-04-21
Posts: 57

Re: The backlight level is no longer adjustable

f_fouad wrote:

nvidia and nvidia-utils to the latest revision of 495 series. You should downgrade nvidia-lts also if you have LTS kernel installed.

Thanks, that works.

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#12 2022-04-07 23:01:51

onestone
Member
Registered: 2015-04-17
Posts: 3

Re: The backlight level is no longer adjustable

Looks like a fix for that is coming for KDE users, in Plasma 5.25 (scheduled to be released on June 14): https://invent.kde.org/plasma/powerdevi … 2c94ecf884

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