I had this problem on my HP Folio 13 both on the old Ubuntu 12.10 and the new Ubuntu 13.04.
I have fixed it by editing /etc/default/grub and changing:
GRUB_CMDLINE_LINUX=""
into:
GRUB_CMDLINE_LINUX="acpi_backlight=vendor"
And eventually by running:
sudo update-grub
sudo reboot
During this entire operation the screen was completely dark. In order to see anything I had to put a very bright lamp against the screen.
I don't see how this bug should be a duplicate of bug #568611. This bug is about the screen back-light not working. Bug #568611 is about the screen controls for increasing and reducing brightness not working.
I had this problem on my HP Folio 13 both on the old Ubuntu 12.10 and the new Ubuntu 13.04.
I have fixed it by editing /etc/default/grub and changing:
GRUB_CMDLINE_ LINUX=" "
into:
GRUB_CMDLINE_ LINUX=" acpi_backlight= vendor"
And eventually by running:
sudo update-grub
sudo reboot
During this entire operation the screen was completely dark. In order to see anything I had to put a very bright lamp against the screen.
I don't see how this bug should be a duplicate of bug #568611. This bug is about the screen back-light not working. Bug #568611 is about the screen controls for increasing and reducing brightness not working.