On Wed, 12 Jul 2006, David Brownell wrote: > > Is that last bit really right? The PM core records each device's power > > state when beginning a system sleep, and it tries to arrange to leave the > > device in that same state when the sleep ends. This may involve a > > transition through the fully-on state... I'm not clear on the details. > > I think the PM core should stop recording _its_ notion of the power state, > but that's a different discussion. > > Yes that bit is right, it's just emphasizing that there _is_ a state machine > in the driver (or should be!), and that with runtime power management it's > not going to be in lock-step with system suspend/resume transitions. That > is after all the whole point of runtime device PM: to decouple from those > system-wide transitions so that "system on" needn't imply "device on". One oddity worth mentioning somewhere is that the PM core will never ask a driver to make a transition between two states unless one of them is ON. This can sometimes lead to unexpected effects, some of which might show up during a system resume. Alan Stern
