I just tested it on my Thinkpad X1 (haswell) and the fix works. However, there is a side effect. Connecting and Disconnecting the Power resets the brightness to maximum. Not sure how to go about working around this.
anmar On 26 February 2014 23:14, madbiologist <1098...@bugs.launchpad.net> wrote: > The upstream 3.14-rc4 kernel also contains this commit: > > author Rafael J. Wysocki > committer Rafael J. Wysocki > commit a6940190ac15c361862a1a8f50a2072db7184749 > tree c73be15646c6418f77a94fede3afc7eabd589dd6 > parent 0e9f81d3b7cd0649a3bc437391b6a0650f98f844 > > Revert "ACPI: Blacklist Win8 OSI for some HP laptop 2013 models" > > This reverts commit 2d4054d84224 (ACPI: Blacklist Win8 OSI for some HP > laptop 2013 models) that is not necessary any more after previous commit > 1811fcb029fa (ACPI / video: Add systems that should favour native > backlight interface). > > Requested-by: Takashi Iwai > Tested-by: Mika Westerberg > Signed-off-by: Rafael J. Wysocki > > -- > You received this bug notification because you are subscribed to a > duplicate bug report (1121951). > https://bugs.launchpad.net/bugs/1098216 > > Title: > Regression in brightness control on Lenovo Thinkpad X230 (+tablet) and > X1 Carbon > > Status in The Linux Kernel: > In Progress > Status in “linux” package in Ubuntu: > Triaged > Status in “linux” package in Fedora: > Unknown > > Bug description: > == 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 > > === 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 > > === 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 > 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: > > WORKAROUND: > > Add to /etc/default/grub > in the variable "GRUB_CMDLINE_LINUX_DEFAULT": > > acpi_osi=\"!Windows 2012\" > > e.g: > > GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=\"!Windows 2012\"" > > Then run "sudo update-grub". > > To manage notifications about this bug go to: > https://bugs.launchpad.net/linux/+bug/1098216/+subscriptions -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1098216 Title: Regression in brightness control on Lenovo Thinkpad X230 (+tablet) and X1 Carbon Status in The Linux Kernel: In Progress Status in “linux” package in Ubuntu: Triaged Status in “linux” package in Fedora: Unknown Bug description: == 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 === 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 === 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 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: WORKAROUND: Add to /etc/default/grub in the variable "GRUB_CMDLINE_LINUX_DEFAULT": acpi_osi=\"!Windows 2012\" e.g: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=\"!Windows 2012\"" Then run "sudo update-grub". To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1098216/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
