Comment 34 for bug 203537

Interesting... with iommu=soft, suspend/hibernate/resume works, but it seems to confuse the graphics card driver. My laptop has a Nvidia GeForce Go 7600 (256MB), and before suspending, adjusting brightness with nvclock works just fine. After resuming, the display is at maximum brightness and nvclock doesn't work anymore.

$ nvclock -S 40
Error!
Smartdimmer is only supported on certain laptops using a Geforce 6200/7x00Go. If you want support on your laptop contact the author.

This is small potatoes, though. Getting suspend/resume working again is huge :-)