On Sat, 2005-03-05 at 10:37 -0500, Alan Stern wrote: > Now that 2.6.11 is out, we can start to address a number of important > issues for power management. This overview discusses some of them, > the things I have run across in my own work. > > > Up to now, the PM development effort has been concerned primarily with > system-wide sleep transitions, things like Suspend-To-RAM (STR) and > Suspend-To-Disk (STD). (A more general, less PC-centric description > would call these states "deep sleep" and "shallow sleep". A third > possible state, which some people might be in favor of, is Standby or > "very shallow sleep".) The important thing here is that these involve > global transitions, affecting every device in the system. Also, they > don't involve many policy decisions (which clocks to turn off and so > on), and in any case such decisions are outside the scope of the PM > core. > .../... Ok, I'll need to take more time re-reading this and giving you a more complete answer, but a quick note for now: I have been thinking about a model that would help deal with both "local" suspend and deal with dependencies. For example, a device may idle suspend, and the parent may want to be notified so that when all the childs are idle-suspended, it may suspend the bus. That sort of things. I have some idea based on a definition of power states as an array in the driver, where the driver exposes the parent/child state dependencies and exposes a state name to sysfs. I posted some blurb about this a while ago on this list btw. Ben.
