https://bugs.freedesktop.org/show_bug.cgi?id=67002
--- Comment #4 from Alex Deucher agd5f@yahoo.com --- The atombios messages are due to bug 67043. You can revert the patch referenced in that bug to fix that. danvet supposed has a v2 of that patch which doesn't break resume.
Also, does it work any better if you drop all the pm-suspend quirks? You shouldn't need them for KMS.