Re: [PATCH 0/8] Suspend block api (version 6)

[Tony Lindgren <tony@atomide.com>]

* Matthew Garrett <mjg@redhat.com> [100511 09:41]:
> On Tue, May 11, 2010 at 09:36:33AM -0700, Tony Lindgren wrote:
> > OK, so can the suspend blocker then become just:
> > 
> > # Block suspend while idle, system stays running
> > # echo default > /sys/power/policy
> > 
> > and the when it's OK to suspend:
> > 
> > # Allow suspend while idle, system suspends when it hits kernel idle loop
> > # echo opportunistic > /sys/power/policy
> > 
> > or do you still need something more to ensure the data gets into your
> > app and be handled?
> 
> Yes. You still need suspend blocks.

Maybe not if echo opportunistic > /sys/power/policy gets cleared by
the kernel if the kernel idle loop can't make it. That means something
has blocked the suspend attempt in a driver for example. The system
keeps running, and the userspace can deal with the situation.
 
> > The part I really don't like is the idea of patching all over the drivers
> > and userspace for the wakelocks/suspendblocks.
> 
> I don't like the idea either, but given that nobody has actually 
> provided any other ideas that would actually work then I don't think 
> we've got a great deal of choice.

If the opportunistic kernel flag is one time attempt only, then you
could take care of the wakelock/suspendblock handling in the userspace
completely. And once the userspace wakelock/suspendblock is cleared,
the userspace can again echo opportunistic > /sys/power/policy.

Regards,

Tony