linux-kernel - RE: [PATCH 5/5] hwspinlock/core: call pm_runtime_put in pm_runtime_get

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Date:	Fri, 5 Apr 2013 13:13:09 +0000
From:	"Li, Fei" <fei.li@...el.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Ohad Ben-Cohen <ohad@...ery.com>,
	"Liu, Chuansheng" <chuansheng.liu@...el.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 5/5] hwspinlock/core: call pm_runtime_put in
 pm_runtime_get_sync failed case

> -----Original Message-----
> From: Rafael J. Wysocki [mailto:rjw@...k.pl]
> Sent: Friday, April 05, 2013 7:42 PM
> To: Ohad Ben-Cohen; Liu, Chuansheng
> Cc: Li, Fei; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH 5/5] hwspinlock/core: call pm_runtime_put in
> pm_runtime_get_sync failed case
> 
> On Friday, April 05, 2013 01:39:58 PM Rafael J. Wysocki wrote:
> > On Friday, April 05, 2013 09:27:40 AM Ohad Ben-Cohen wrote:
> > > Hi Li,
> > >
> > > On Thu, Feb 28, 2013 at 10:02 AM, Li Fei <fei.li@...el.com> wrote:
> > > >
> > > > Even in failed case of pm_runtime_get_sync, the usage_count
> > > > is incremented. In order to keep the usage_count with correct
> > > > value and runtime power management to behave correctly, call
> > > > pm_runtime_put(_sync) in such case.
> > >
> > > Is it better then to call pm_runtime_put_noidle instead? This way
> > > we're sure to only take care of usage_count without ever calling any
> > > underlying pm handler.
> >
> > Both would break code that does
> >
> >  pm_runtime_get_sync(dev);
> >
> >  <device access>
> >
> >  pm_runtime_put(dev);
> >
> > without checking the result of pm_runtime_get_sync() - which BTW is
> completely
> > unnecessary in the majority of cases.
> 
> Sorry, scratch that.  I should have had a closer look at the context.
> 
> Yes, it better to call pm_runtime_put_noidle() in this case.
> 
Thanks for your feedback.
I'll upload patch V2 for this topic.

Thanks,
Fei

> Thanks,
> Rafael
> 
> 
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.