On Fri, Oct 05, 2012 at 09:43:32AM +0200, Ulf Hansson wrote:

> To be able to deactivate resourses in suspend, the resourses must
> first be surely active. This is done with a pm_runtime_get_sync.
> Once the resourses are restored to active state again in resume,
> the runtime pm usage count can be decreased with a pm_runtime_put.

The PM core will ensure devices are runtime resumed before we enter
suspend precisely due to this sort of issue.