** Description changed: + == Raring SRU Justification == + + Impact: A number of ThinkPad models have a workaround in the ACPI + backlight implementation for Windows 8 that more or less completely + breaks backlight control. + + Fix: Add an OSI quirk to no longer claim to be Windows 8 on these + machines, causing the firmware to revert to the older, working behavior. + + Test Case: Verified on LP #1098216 and bugzill.kernel.org #51231. + + --- + Something changed between the 3.5 and the 3.7 kernel, leading to broken brightness control on my Thinkpad x230. Here are some test results: == 3.5.0-21-generic == === Post-boot values === /sys/class/backlight: - - intel-backlight - + actual_brightness => 4438 - + bl_power => 0 - + brightness => 4438 - + max_brightness => 4438 - - acpi_video0 - + actual_brightness => 15 - + bl_power => 0 - + brightness => 15 - + max_brightness => 15 + - intel-backlight + + actual_brightness => 4438 + + bl_power => 0 + + brightness => 4438 + + max_brightness => 4438 + - acpi_video0 + + actual_brightness => 15 + + bl_power => 0 + + brightness => 15 + + max_brightness => 15 === Tests === echo 0 > acpi_video0/brightness => works echo 0 > intel_backlight/brightness => works == 3.8.0-0-generic == === Post-boot values === /sys/class/backlight: - - intel-backlight - + actual_brightness => 4438 - + bl_power => 0 - + brightness => 4438 - + max_brightness => 4438 - - acpi_video0 - + actual_brightness => 100 - + bl_power => 0 - + brightness => 100 - + max_brightness => 100 + - intel-backlight + + actual_brightness => 4438 + + bl_power => 0 + + brightness => 4438 + + max_brightness => 4438 + - acpi_video0 + + actual_brightness => 100 + + bl_power => 0 + + brightness => 100 + + max_brightness => 100 === Tests === echo 0 > acpi_video0/brightness => doesn't do anything echo 0 > intel_backlight/brightness => works - --- + --- ApportVersion: 2.8-0ubuntu1 Architecture: amd64 CheckboxSubmission: 12108b8b8b67d760cdd84f1b9574e7f3 CheckboxSystem: bb422ca46d02494cdbc459927a98bc2f DistroRelease: Ubuntu 13.04 InstallationDate: Installed on 2012-09-02 (129 days ago) InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120902) MarkForUpload: True Package: linux (not installed) ProcEnviron: - LANGUAGE=en_US:en - TERM=xterm - PATH=(custom, no user) - LANG=en_US.UTF-8 - SHELL=/bin/bash + LANGUAGE=en_US:en + TERM=xterm + PATH=(custom, no user) + LANG=en_US.UTF-8 + SHELL=/bin/bash ProcVersionSignature: Ubuntu 3.8.0-0.1-generic 3.8.0-rc3 Tags: raring Uname: Linux 3.8.0-0-generic x86_64 UnreportableReason: The running kernel is not an Ubuntu kernel UpgradeStatus: No upgrade log present (probably fresh install) UserGroups:
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1098216 Title: Regression in brightness control on Lenovo Thinkpad X230 and X1 Carbon To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1098216/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
