Backlight display dims completely after update to kernel 7.0.0-28 (Dell Latitude 7280)

Hardware Support
1

System Specifications:

  • Device: Dell Latitude 7280
  • OS: Zorin OS
  • Working Kernel: 6.17.0-35-generic
  • Problematic Kernel: 7.0.0-28-generic

Issue Description: After a recent system update to kernel 7.0.0-28-generic, the display backlight functions normally during BIOS boot, but instantly dims to near-zero brightness as soon as Zorin OS loads. Adjusting display brightness via hardware keys or OS settings has no effect.

Testing standard ACPI boot parameters (acpi_backlight=native and acpi_backlight=vendor) did not resolve the issue.

Diagnostic Clues: Checking the BIOS Power Events log reveals repeated ACPI power transitions upon OS initialization:

  • Power off - ACPI power management
  • Followed shortly by: Power on - not applicable

This indicates an ACPI power-state management conflict introduced in kernel 7.0.0-28, causing the system to mismanage power to the display backlight inverter.

Workaround / Solution: Booting into the previous stable kernel (6.17.0-35-generic) via the GRUB menu completely resolves the issue, restoring full screen brightness and normal backlight control.

2

I suppose I could mark this as the Solution for now. But maybe a fix will turn up in a later 7.0.0-?? kernel sometime downstream.
It would look better if you had done a second post for your Workaround/Solution text. The solution would then be attributed to you, not me. Zab

3

I did this in Terminal --> sudo nano /etc/default/grub
And changed --> GRUB_DEFAULT="Advanced options for Zorin OS>Zorin OS, with Linux 6.17.0-35-generic"

4

Welcome to the Forum!

Here, You could update to the Version 6.17.0-40-generic if You want. That exists and came out before the 7.0 Kernel was released.

You can, but You don't have to of Course.