Thank you for taking the time to report this issue and for providing the diagnostic information. I appreciate your help.
A newer kernel includes a change that may restore brightness control on this laptop. Please start with Mainline 7.1.4. If you are already comfortable building Ubuntu kernels, there is also an advanced option for Ubuntu kernel 7.0.0-28. Start with Ubuntu Mainline kernel 7.1.4 1. I suggest testing Ubuntu Mainline kernel 7.1.4. It includes a change that may restore working brightness controls on this laptop. 2. This test will show whether that change fixes the brightness problem seen with the current Ubuntu kernel. 3. The official Ubuntu Mainline build for the reported amd64 architecture is available here: https://kernel.ubuntu.com/mainline/v7.1.4/amd64/ General Ubuntu instructions for installing, booting, checking, and removing Mainline kernels are available here: https://wiki.ubuntu.com/Kernel/MainlineBuilds This is an unsupported test kernel, not a normal Ubuntu update. Its image is unsigned and may not start with Secure Boot enabled. If it does not start, please report that result rather than changing your Secure Boot settings solely for this test. 4. After booting the test kernel, check the full brightness range with both keyboard hotkeys and desktop controls. Repeat after suspend and resume, and confirm that the screen itself becomes brighter or darker. 5. After booting, please run this command and include its output: uname -r 6. Please report whether brightness control worked before and after suspend, along with any installation or startup error. Advanced option: build Ubuntu kernel 7.0.0-28 with fix f30fddb4402313aa5301a74d721638d343395269 This is a lower-priority option for someone who is already comfortable building Ubuntu kernels. It is not required for the Mainline comparison above. The test would apply Revert drm/i915/backlight: Remove try_vesa_interface (f30fddb4402313aa5301a74d721638d343395269) to the Ubuntu 7.0.0-28 kernel source. This change may make the brightness keys and desktop brightness control affect the screen again. Source for the fix: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f30fddb4402313aa5301a74d721638d343395269 Official Ubuntu instructions for obtaining the source, applying a patch, building packages, installing the kernel, and checking the result: https://ubuntu.com/kernel/docs/latest/how-to/develop-customise/build- kernel/ If you choose this advanced test, please check the full brightness range before and after suspend. After booting the test kernel, run this command and include its output: uname -r Please report whether the screen itself becomes brighter or darker, along with any installation or startup error. ** Changed in: linux (Ubuntu) Importance: Undecided => High ** Changed in: linux (Ubuntu) Status: New => Confirmed ** Changed in: linux (Ubuntu) Assignee: (unassigned) => Krystian Kaniewski (kkaniewski) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2161309 Title: Backlight regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161309/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
