linux-kernel - Re: [linux-pm] Null suspend/resume functions

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Message-ID: <20091117115236.GB1376@ucw.cz>
Date:	Tue, 17 Nov 2009 12:52:36 +0100
From:	Pavel Machek <pavel@....cz>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Kuninori Morimoto <morimoto.kuninori@...esas.com>,
	Magnus Damm <damm@...nsource.se>, alsa-devel@...a-project.org,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [linux-pm] Null suspend/resume functions

On Mon 2009-11-16 15:30:00, Mark Brown wrote:
> On Mon, Nov 09, 2009 at 01:31:36PM +0000, Mark Brown wrote:
> > On Mon, Nov 09, 2009 at 10:58:58AM +0000, Mark Brown wrote:
> > > On Mon, Nov 09, 2009 at 11:54:47AM +0900, Kuninori Morimoto wrote:
> 
> Any chance someone from the PM side could comment on the issue below?
> 
> > > > +static int fsi_runtime_nop(struct device *dev)
> > > > +{
> > > > +	/* Runtime PM callback shared between ->runtime_suspend()
> > > > +	 * and ->runtime_resume(). Simply returns success.
> > > > +	 *
> > > > +	 * This driver re-initializes all registers after
> > > > +	 * pm_runtime_get_sync() anyway so there is no need
> > > > +	 * to save and restore registers here.
> > > > +	 */
> > > > +	return 0;
> > > > +}
> > > 
> > > This sets off alarm bells but it's perfectly reasonable, especially with
> > > platforms able to put things into a low power state with no explicit
> > > driver code now they can do power domain style things like SH.  I've
> > > CCed in the PM folks since this seems like a perfectly reasonable use
> > > case which ought to be handled more nicely.

I believe that having few nop functions around the tree should not be
huge problem. If it is, you can introduce one shared top function into
the core...
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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