Saturday, December 3, 2011

Hybrid graphics on the 3820tg running Ubuntu 11.04 (natty)

My Acer TimeLineX 3820TG has served me pretty well over the last year.  The only complaint I have against the laptop is the fact that it has "hybrid graphics".

The concept is nice -- you use the full powered Radeon HD5650 w 1gb of ram whenever you want performance (and plugged into power) and the integrated Intel GPU whenever you want power savings.

Unfortunately it doesn't play nice with Linux.  Their are no official drivers to support it.

Some of the issues encountered are:

  1. very loud fans
  2. laptop runs hot 
  3. unpredictable suspend 
  4. VERY poor battery life
  5. computer freezes at bootup (B[lack]SOD)
To fix these issues you'll have to do some tweaking to the configuration of the system. 

The first thing you will want to do is turn off the Radeon GPU. To be honest, there's no real reason to use it under Linux unless you are doing some heavy 3D gaming.  The Intel chipset is fine for normal 3d acceleration (esp., running HD video, running compiz, etc).

In order to fix issues 1-4 you need to use 'switcheroo' to switch to the chipset you want to use (i.e. the intel chipset). 

Switcheroo and Radeon blacklisting

First, open /etc/modprobe.d/blacklist.conf as root (I always use "gksu nautilus" to open the file manager as root and then navigate there). Once you have opened it with a text editor add the following line add the end:
blacklist radeon
Once you have done that, save the file and close the text editor.
Now  open /etc/rc.local (still as root) and add the following lines BEFORE  'exit 0'
modprobe radeon 
 echo OFF > /sys/kernel/debug/vgaswitcheroo/switch
Again, save the file. Now the radeon module will be re-loaded, vgaswitcheroo will be reenabled and the ATI card will be turned off. Cooler, quieter and better battery life.

This should fix the issues, however, if you continue to have the Black Screen of Death on bootup (i.e., the system freezes on start-up) it's likely the known issue with the 2.6.38 kernel (used in natty).

In order to fix it, you can install the patched linux kernels found on this post:
https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+bug/727620/comments/160

you'll need to know if you are running 32bit or 64bit Linux and choose the appropriate files. For me, I've installed the folliwing on my 64bit system (in this order):


References: 
https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+bug/727620
http://askubuntu.com/questions/39562/radeon-module-boot-problems

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