> On Thu, 12 Jul 2007, Huang, Ying wrote:
>
> > On Thu, 2007-07-12 at 00:03 -0700,
david@lang.hm wrote:
> >>>
> >>> The kexec jump is the first step, maybe the simplest step. There are
> >>> many other issues to be resolved, at least the following ones.
> >>>
> >>> 1. Separate device suspend from device hibernate.
> >>
> >
> > Maybe my usage of terminology has some problem. But, the "device
> > hibernate" here means put device into quiescent state and save the
> > device state, but do not put device into low power state.
>
> is there really enough savings (in time or otherwise) to make it worth
> splitting this into two steps? for suspend-to-ram we definantly will need
> to option to go all the way to a low power state, there's significant
> extra complexity if you also have a state between normal operation and
> this low power state.
>
> it may be worth doing if the low-power state is expensive (in time or
> effort) to get to or from and the lesser state allows the computer overall
> to save power (like the different cpu C states)
>
> but I suspect that the number of drivers where this is worth doing is
> relativly small, and it may be a better approach to start off with just
> putting everything into the low-power state until some drive shows up that
> makes it worth adding the intermediate state to the system (and drivers
> wouldn't have to change, if they only support one suspend state it's the
> low-power one, if they support more then higher layers choose which ones
> to move to)
