[linux-pm] [RFD] Automatic suspend

[Rafael J. Wysocki]

On Friday 27 February 2009, Matthew Garrett wrote:
> On Fri, Feb 27, 2009 at 03:22:39PM +0100, Rafael J. Wysocki wrote:
> > On Friday 27 February 2009, Pavel Machek wrote:
> > > Wakelocks done right are single atomic_t... and if you set it to 0,
> > > you just unblock "sleeper" thread or something. Zero polling and very
> > > simple...
> > 
> > Except that you have to check all of the wakelocks periodically in a loop =>
> > polling.  So?
> 
> Why do you need to check them? If you're taking this approach you just 
> have something like:
> 
> suspend_unblock() {
> 	if (atomc_dec_and_test(&suspend_lock))
> 		suspend();
> }
> 
> and then check that the lock count is still 0 after device_suspend(). 
> There's no need to poll.

I was talking about wakelocks as originally proposed.

Using a refcount along with per-driver and per-process flags (probably two
refcounts would be more efficient in fact) is the latest idea and I agree it
wouldn't require polling.  However, if you refer to that, please don't use the
name "wakelock". :-)

Thanks,
Rafael