linux-kernel - Re: System suspend states and device driver suspend() callback

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Date:	Sat, 17 Aug 2013 01:53:36 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Li Yang-R58472 <r58472@...escale.com>
Cc:	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: System suspend states and device driver suspend() callback

On Friday, August 16, 2013 05:13:42 PM Li Yang-R58472 wrote:
> 
> 在 2013-8-16，下午7:22，"Rafael J. Wysocki" <rjw@...k.pl> 写道：
> 
> > On Friday, August 16, 2013 04:06:26 PM Li Yang wrote:
> >> Hi Guys,
> >> 
> >> Is there a standard way for the device drivers to know if the system
> >> is going to “standby” mode or “mem” mode when the suspend() callbacks
> >> are called?
> > 
> > No, there's none.
> > 
> > What do you need that for?
> 
> Some chips like ours are putting the on-chip devices into different low
> power states when entering different system low power states.  When we enter
> system standby, on-chip devices are clock gated.  While entering suspend to
> ram, on-chip devices are power gated.  We want to driver to act differently
> too when entering different suspend states.

Can you possibly use platform suspend operations to implement that (in analogy
with ACPI suspend operations)?

Rafael

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