I can confirm adding "acpi_osi=Linux" fixes the problem on my Eee PC T101MT. If I also add "acpi_backlight=vendor", screen brightness feedback also works, but I can't reach maximum brightness then. When I omit it, brightness control works fine and the screen gets as bright as in Windows, except that there is no feedback.
I can confirm adding "acpi_osi=Linux" fixes the problem on my Eee PC T101MT. If I also add "acpi_backlight =vendor" , screen brightness feedback also works, but I can't reach maximum brightness then. When I omit it, brightness control works fine and the screen gets as bright as in Windows, except that there is no feedback.