On Wed, 2011-02-09 at 23:42 +0000, Alan Stern wrote:
> In fact there already is a "fast suspend & resume" path in the PM core.
> It's the freeze/thaw procedure used when starting to hibernate. The
> documentation specifically says that drivers' freeze methods are
> supposed to quiesce their devices but not change power levels. In
> addition, the thaw method is invoked as part of recovery from a failed
> hibernation attempt, so it already has the "cancel" semantics that xen
> seems to want.
Sounds like that would work and I would much prefer to simply make
correct use of the core functionality.
So PMSG_FREEZE is balanced by either PMSG_RECOVER or PMSG_THAW depending
on whether the suspend was cancelled or not? So the sequence of events
is something like:
dpm_suspend_start(PMSG_FREEZE);
dpm_suspend_noirq(PMSG_FREEZE);
sysdev_suspend(PMSG_QUIESCE);
cancelled = suspend_hypercall()
sysdev_resume();
dpm_resume_noirq(cancelled ? PMSG_RECOVER : PMSG_THAW);
dpm_resume_end(cancelled ? PMSG_RECOVER : PMSG_THAW);
?
(For comparison we currently have:
> > > dpm_suspend_start(PMSG_SUSPEND);
> > >
> > > dpm_suspend_noirq(PMSG_SUSPEND);
> > >
> > > sysdev_suspend(PMSG_SUSPEND);
> > > /* suspend hypercall */
> > > sysdev_resume();
> > >
> > > dpm_resume_noirq(PMSG_RESUME);
> > >
> > > dpm_resume_end(PMSG_RESUME);
)
Ian.
--
Ian Campbell
Current Noise: Neil Young - Angry World
If only one could get that wonderful feeling of accomplishment without
having to accomplish anything.
_______________________________________________
linux-pm mailing list
linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linux-foundation.org/mailman/listinfo/linux-pm
