Hi I'm experiencing a similar problem on my Acer Nitro; the brightness I'm experiencing a frustrating brightness regression on my Acer Nitro AN515-58 laptop (Intel Alder Lake-P / RTX 2050) after updating the kernel through the Mint Update Manager.
Everything works flawlessly on kernel 7.0.0-14 (physical brightness keys change the screen light just fine). However, as soon as the system boots into kernel 7.0.0-28, the screen gets stuck at 100% maximum brightness. The system creates the usual `/sys/class/backlight/intel_backlight` folder, but changing the values there has absolutely no physical effect on the panel. To save everybody's time, here is a summary of what I've already tried to fix it: 1. **Modifying ACPI parameters in GRUB:** I tried editing the GRUB configuration by testing several compatibility flags one by one, specifically 'acpi_backlight=native', 'acpi_backlight=vendor', and 'acpi_backlight=video'. I updated GRUB after each try, but none of them restored physical control of the backlight. 2. **Manual tests in the terminal (`/sys`):** The file `/sys/class/backlight/intel_backlight/max_brightness` reports a limit of 32767. If I use commands like echo to manually force lower values (e.g., 10000 or 5000) directly into the 'brightness' file, the software register updates, but the panel physically remains stuck at 100% blinding brightness. I checked dmesg on the broken kernel (.28) and found a severe ACPI error right during boot: [ 3.179431] ACPI BIOS Error (bug): Could not resolve symbol [\_TZ.ETMD], AE_NOT_FOUND [ 3.179518] ACPI Error: Aborting method \_SB.IETM._OSC due to previous error It seems the newer kernel is aborting the Intel IETM method due to a BIOS symbol mismatch, completely breaking the backlight communication with the hardware. For now, I had to downgrade and pin kernel 7.0.0-14 to keep my eyes from burning, but I wanted to report this here in case other Nitro users are hitting the same wall, or if this can be tracked/patched upstream. Any advice or workarounds for newer kernels are highly appreciated. Thanks! :D :D :D -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2161204 Title: Regression: Extremely dim internal display on Acer Aspire 5 with kernel 7.0.0-28 (Intel i915), kernel 6.14.0-37 works correctly To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161204/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
