Had the same issue after upgrading from lucid to precise an HP Pavilion g6. Solved with:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"
Thanks a lot!
Had the same issue after upgrading from lucid to precise an HP Pavilion g6. Solved with:
GRUB_CMDLINE_ LINUX_DEFAULT= "quiet splash acpi_osi=Linux acpi_backlight= vendor"
Thanks a lot!