Secondly, I can boot and use Ubuntu 12.04 on a HP Compaq laptop with Radeon HD 6310 graphics (without using nomodeset), so it could be something to do with the kernel's detection/setup of your laptop's display panel. I don't suppose you know whether it is an eDP or not?
Firstly, instead of a "basic graphics" mode, you can boot Ubuntu with the "nomodeset" kernel boot option added to your GRUB command line. See https:/ /help.ubuntu. com/community/ Grub2/Troublesh ooting# Editing_ the_GRUB_ 2_Menu_ During_ Boot
Secondly, I can boot and use Ubuntu 12.04 on a HP Compaq laptop with Radeon HD 6310 graphics (without using nomodeset), so it could be something to do with the kernel's detection/setup of your laptop's display panel. I don't suppose you know whether it is an eDP or not?