Comment 3 for bug 1628725

I was able to fix this by editing my grub settings.

http://askubuntu.com/questions/162409/brightness-not-working-on-an-hp-pavilion-dv6-with-a-ati-radeon-hd6770m

The file i edit is

 /etc/default/grub

Before fix (when it didnt work)

GRUB_CMLINE_LINUX_DEFAULT="quiet splash nomodeset"

The reason I had added nomodeset was to get my virtual consoles to show up when i hit ctrl alt f3

After fix - (suspend works properly again)

GRUB_CMDLINE_LINUX_DEFAULT="acpi_backlight=vendor"