Brightness resets to 0 after every reboot


Could you please open a terminal then type in sudo nano /etc/default/grub please?

Once in the editor, use the arrows key on your keyboard to navigate toward the line where it says GRUB_CMDLINE_LINUX_DEFAULT=
Then add acpi_backlight=vendor to the end, but befor the last " (quotation mark)!

Hit CTRL + S to save, then CTRL + X to exit the editor.

Finally, punch in sudo update-grub


Have a wonderful day! :sweat_smile:

Thanks for your help
This is my grub now:

GRUB_CMDLINE_LINUX_DEFAULT="quiet apparmor=1 security=apparmor resume=UUID=d2ac6ecc-cb0e-4f82-b617-1792c08b94b3 udev.log_priority=3 acpi_backlight=vendor"

# If you want to enable the save default function, uncomment the following
# line, and set GRUB_DEFAULT to saved.

# Preload both GPT and MBR modules so that they are not missed
GRUB_PRELOAD_MODULES="part_gpt part_msdos"

# Uncomment to enable booting from LUKS encrypted devices

# Uncomment to use basic console

# Uncomment to disable graphical terminal

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command 'videoinfo'

# Uncomment to allow the kernel use the same resolution used by grub

# Uncomment if you want GRUB to pass to the Linux kernel the old parameter
# format "root=/dev/xxx" instead of "root=/dev/disk/by-uuid/xxx"

# Uncomment to disable generation of recovery mode menu entries

# Uncomment and set to the desired menu colors.  Used by normal and wallpaper
# modes only.  Entries specified as foreground/background.

# Uncomment one of them for the gfx desired, a image background or a gfxtheme

# Uncomment to get a beep at GRUB start
#GRUB_INIT_TUNE="480 440 1"

The problem still exists


Could you please provide me the output of ls /sys/class/backlight please?

Thank you!

Yes of course


Wow that’s the exact thing I see in error when I boot my laptop
And also these are inside amdgpu_bl0 :

-r--r--r-- 1 root root 4096 Oct  5 14:25 actual_brightness
-rw-r--r-- 1 root root 4096 Oct  5 14:25 bl_power
-rw-r--r-- 1 root root 4096 Oct  5 14:04 brightness
lrwxrwxrwx 1 root root    0 Oct  5 14:25 device -> ../../../0000:05:00.0
-r--r--r-- 1 root root 4096 Oct  5 13:36 max_brightness
drwxr-xr-x 2 root root    0 Oct  5 14:25 power
-r--r--r-- 1 root root 4096 Oct  5 14:25 scale
lrwxrwxrwx 1 root root    0 Oct  5 13:36 subsystem -> ../../../../../../class/backlight
-r--r--r-- 1 root root 4096 Oct  5 13:36 type
-rw-r--r-- 1 root root 4096 Oct  5 13:36 uevent

Thank you!

Instead of acpi_backlight=vendor in your grub configuration, please change it to acpi_backlight=amdgpu_bl0 !

May also mask the acpi_video0 by imploring sudo systemctl mask acpi_video0

Hope that may help!

Ok now it got worse :joy:
Away from the brightness set to 100% every time, the errors I see when booting are:

Failed to start Load/Save #tness of backlight:amdgpu_bl0
Failed to start Load/Save #tness of backlight:acpi_video0


I changed acpi_backlight to native based on this question and the error Failed to start Load/Save #tness of backlight:acpi_video0 vanished.
But I still see amdgpu_bl0

Oh no :joy:

Might as well try to mask amdgpu as well, see if it does something…

sudo systemctl mask amdgpu_bl0

I run it and restarted but still no result
Also my brightness problem is still there :smiley:

Hmmm :thinking:

Lets try to sudo systemctl unmask acpi_video0 , then set acpi_backlight=video0 in grub …

Again, those two errors showed up
What’s the problem?

Have you ran sudo update-grub , may I ask?

Yes I ran it and restarted :slight_smile:

Alright, sudo systemctl unmask amdgpu_b10 then add acpi_osi=Linux acpi_backlight=vendor to your grub config. :thinking:

Unfortunately, the problem still exists :frowning_face:
I mean both error on boot and brightness issue

Okay, could you please roll back to kernel57, see if thats the issue?

Ok now my kernel is:
And the error on boot disappeared(Thanks!!)
But still, my brightness is set to 100%

Hm, then lets remove acpi_osi=Linux from grub, and change to acpi_backlight=native :grinning_face_with_smiling_eyes:

Still no chance :joy:
I guess grub is getting angry with me :joy:

Hm, getting out of ideas😬

Try to completely remove the acpi backlight string in grub…

And now the error Failed to start Load/Save #tness of backlight:acpi_video0 shows up again