Public bug reported:
After upgrading from Linux 7.0.0-14-generic to 7.0.0-28-generic on
Ubuntu 26.04 LTS, the built-in display becomes significantly dim
immediately after boot. The brightness slider reports 100%, but the
screen remains visibly darker. Reverting to 7.0.0-14 restores normal
brightness.
Hardware:
Dell Latitude 5420
Intel Tiger Lake Iris Xe Graphics (8086:9a49)
Driver: i915
Backlight: intel_backlight
Testing performed:
✅ Ubuntu Live USB: normal brightness
✅ Fresh Ubuntu install (no updates during install): normal brightness
✅ Windows: normal brightness
✅ Linux Mint: normal brightness
✅ Updated general packages: no issue
✅ Updated GNOME (gdm3, mutter): no issue
✅ Updated linux-firmware-intel-graphics: no issue
❌ Upgraded only to Linux kernel 7.0.0-28-generic: display immediately became
dim after reboot
✅ Restored Timeshift snapshot (kernel 7.0.0-14): brightness returned to normal
Conclusion:
The regression appears to be introduced by Linux kernel 7.0.0-28-generic
rather than GNOME, Intel graphics firmware, or hardware. The issue is
reproducible and disappears immediately when booting or restoring the
previous kernel (7.0.0-14).
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: 7.0.0-28 brightness kernel
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https://bugs.launchpad.net/bugs/2161763
Title:
Dell Latitude 5420 brightness regression with Linux kernel
7.0.0-28-generic
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