For the record, adding acpi_osi=\"!Windows 2012\" to grub command-line fixes the same problem on my HP ProBook 430 G1 with similar but slightly different VGA chipset (Intel Corporation Haswell-ULT Integrated Graphics Controller [8086:0a16]). Haven't tried the deb provided by Anthony in comment #31, but I don't suppose they would work, as the fix in blacklist.c seems to be vendor/product specific.
Could this be a more generic Haswell issue? Attaching dmidecode and lspcpi on my HP 430 G1 system. ** Attachment added: "dmidecode.log" https://bugs.launchpad.net/ubuntu/+source/linux-lts-raring/+bug/1231305/+attachment/3909206/+files/dmidecode.log -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1231305 Title: Unable to adjust screen brightness with Intel Haswell-ULT Integrated Graphics Controller [8086:0a26] To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1231305/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
