linux-kernel - Re: [PATCH v5 1/2] PM / sleep: Go direct

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Date:	Mon, 5 Oct 2015 11:07:27 +0200
From:	Pavel Machek <pavel@....cz>
To:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Alan Stern <stern@...land.harvard.edu>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	martyn.welch@...labora.co.uk,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Len Brown <len.brown@...el.com>,
	Kevin Hilman <khilman@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH v5 1/2] PM / sleep: Go direct_complete if driver has no
 callbacks

On Mon 2015-10-05 10:25:45, Tomeu Vizoso wrote:
> On 4 October 2015 at 17:16, Pavel Machek <pavel@....cz> wrote:
> > On Tue 2015-09-29 14:29:19, Tomeu Vizoso wrote:
> >> If a suitable prepare callback cannot be found for a given device and
> >> its driver has no PM callbacks at all, assume that it can go direct to
> >> complete when the system goes to sleep.
> >>
> >> The reason for this is that there's lots of devices in a system that do
> >> no PM at all and there's no reason for them to prevent their ancestors
> >> to do direct_complete if they can support it.
> >
> > Dunno. This sounds like asking for trouble. Even if most devices can handle
> > this, is not this bound to introduce some bugs?
> 
> Hi Pavel,
> 
> in which situations do you think that this could be problematic?

Well.. driver with no PM callbacks probably works "by accident", and now you are changing
its environment. Do you have explanation why it will not break?

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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