Ethan Shalev, if for any reason you encounter any potential collateral issues from acpi_osi=Linux, you could try using a different debug kernel parameter: acpi_backlight=vendor
Despite this, could you please undo any WORKAROUNDs, and test the latest mainline kernel via http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.13-rc2-trusty/ and advise on the results?
Ethan Shalev, if for any reason you encounter any potential collateral issues from acpi_osi=Linux, you could try using a different debug kernel parameter: vendor
acpi_backlight=
Despite this, could you please undo any WORKAROUNDs, and test the latest mainline kernel via http:// kernel. ubuntu. com/~kernel- ppa/mainline/ v3.13-rc2- trusty/ and advise on the results?