A couple of updates. We've applied a patch for raring to quirk acpi_osi="!Windows 2012" for machines known to be affected by this bug. This isn't a long-term solution, but it will keep things working for the time being.
I'm also continuing to pursue a more permanent solution upstream. Towards that end, I've worked up a patch which simply disables use of the ACPI backlight which Windows 8 compatibility is being used. This does have a couple of drawbacks. While most machines should have another backlight interface available to use, some may not. Brightness adjustments using the hotkeys while in a VT are likely to no longer work as well. It will remain possible to work around both of these using acpi_osi="!Windows 2012". I've posted a test build with the new patches at the link below. I'd appreciate any testing to validate that these changes on the various affected machines, and also validation that passing acpi_osi="!Windows 2012" in that build still restores the pre-Win8 behavior. http://people.canonical.com/~sforshee/lp1098216/linux-3.8.0-19.29~lp1098216v201304221819/ -- 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
