Public bug reported:
It is impossible for me to adjust the screen brightness using the slider
in the Gnome menu, nor in the energy settings.
I'm on Ubuntu 20.04.2, the Nvidia 450.102.04 drivers with an xorg session (no
.conf file in /etc/X11/)
I have an Imac 27" end2013.
This happened after the update of the kernel to version 5.8 (hwe), I am
currently with the 5.8.0-41-generic.
The brightness is set to its maximum.
Setting the automatic brightness to 1 doesn't change anything.
You can also adjust the brightness directly on /sys/class/backlight/acpi_video0
with the command :
echo 7 > /sys/class/backlight/acpi_video0/brightness
Nothing changes, even with other values.
In the /sys/class/backlight folder, I only have acpi_video0.
However, I have tried to change the settings:
acpi_backlight=vendor, acpi_backlight=video,acpi_backlight=none, and
acpi_backlight=native, but without success, the slider in the gnome menu
disappears for (vendor, native and none).
When I come back to kernel 5.4.0-65-generic, I can change the brightness
again.
I have the same problem with an install of fedora 33 with kernel 5.9
then 5.10, as well as with the lice-cd (driver gpu = nouveau).
** Affects: ubuntu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1913961
Title:
impossible to adjust the brightness after upgrading the kernel to
version 5.8 (hwe)
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