On 13.10, the brightness works fine but the stepping is screwed up. In
other words, you don't get to access all of the brightness levels the
LCD offers. Instead, you get half the number of steps. It isn't a show
stopper by any stretch so go ahead and get your X1 carbon. It is the
best machine out there ;-)

On 5 January 2014 19:59, Matthew Tucker-Simmons
<email address hidden> wrote:
> I'm using an X1 Carbon with 13.10 and the brightness control works fine.
>
>
> On Wed, Jan 1, 2014 at 11:29 AM, CSRedRat <email address hidden>wrote:
>
>> Fixed? Can i'm buy X1 Carbon? :)
>>
>> --
>> You received this bug notification because you are subscribed to the bug
>> report.
>> 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 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