On Sat, 31 Jan 2009, Linus Torvalds wrote:

For a USB host controller, for example, it really could make sense to do 
that - just leave all the core host controller stuff running, and the only 
thing the "suspend()" callback does is to send the commands to the actual 
devices, it doesn't necessarily touch the host controller itself at all.

Same is quite likely true of things like video graphics adapters. Again, 
for all the same reasons. Think about all those fbcon drivers. They will 
use DMA for things. And again, there are very compelling debugging reasons 
to not suspend them for real until suspend_late (if even then).

		Linus