Ubuntu and the HP Envy 15t-3200

Solution 1:

My Vaio VPCSA had a similar problem.

I replaced a line in /etc/defalut/grub (1):

GRUB_CMDLINE_LINUX="video.allow_duplicates=1 radeon.modeset=1"

It fixed the problem for Ubuntu 12.10. However, that's not enough for Debian/unstable. In addition, I had to add a line to /etc/modprobe.d/blacklist.conf (2):

blacklist radeon

And to /etc/rc.local BEFORE exit 0; (3):

modprobe radeon modeset=1
mount -t debugfs none /sys/kernel/debug/
echo OFF > /sys/kernel/debug/vgaswitcheroo/switch

If you have issues, start with (2). It has reliably resulted in a bootable system, than proceed with (3).