Laptop backlight control regression with 465.24.02

Upgrading my Alienware 17 R4 laptop to the 465.24.02 driver breaks the backlight control. The backlight is very bright (probably 100%) with the 465.24.02 driver and cannot be changed. Reverting back to the 460.67 driver restores the backlight control.

Here is the Nvidia bug report with the 465.24.02 driver installed:

nvidia-bug-report.log.gz (1.2 MB)

[ 0.058646] You have booted with nomodeset. This means your GPU drivers are DISABLED
[ 0.058647] Any video related functionality will be severely degraded, and you may not even be able to suspend the system properly

Please try again with the nomodeset kernel parameter removed.

I reinstalled 465.24.02 and removed the nomodeset kernel parameter when rebooting. The problem persists with 465.24.02. The nomodeset parameter is present for the 460.67 driver and the backlight control works as expected.

In case it is useful, I’ve included the bug report after booting with 465.24.02 and the nomodeset removed.


nvidia-bug-report.log.gz (1.2 MB)

[ 6.576311] audit: type=1130 audit(1618879473.126:108): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg=‘unit=systemd-backlight@backlight:acpi_video1 comm=“systemd” exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=failed’

What would the output of sudo systemctl status systemd-backlight@backlight:acpi_video1 show in the failed state?

Could you maybe also try with the kernel parameter: acpi_backlight=vendor

The output of the systemctl status is:
● systemd-backlight@backlight:acpi_video1.service - Load/Save Screen Backlight Brightness of backlight:acpi_video1
Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
Active: inactive (dead)
Docs: man:systemd-backlight@.service(8)

Using acpi_backlight=vendor makes no difference.

Thanks for the suggestions.

Also tried acpi_backlight=video with 465.24.02 without success.

xbacklight also does not change the backlight brightness. I can use “xrandr --output DP-0 --brightness 0.7” to dim the super bright display, but that is an ugly workaround.

460.73.01 works as expected.

It would be appreciated if someone from nvidia confirmed this regression.

I’m having the same issue tbeckman reported on an Alienware 15 R3 with nvidia driver 465.24.02, while everything works fine using 460.67.

I’d like to add that in /sys/class/backlight/nvidia_0 folder, the values within brightness and actual_brightness do change when using hotkeys or tools like xbacklight, but it looks like they are not honored anymore.

I’m attaching a bug report hoping it may prove helpful: nvidia-bug-report.log.gz (396.8 KB)

This regression is still present in 465.27.