linux-kernel - RE: [PATCH 1/2] pwm: pwm-tiehrpwm: Low power sleep support

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Date:	Wed, 16 Jan 2013 12:14:01 +0000
From:	"Philip, Avinash" <avinashphilip@...com>
To:	Thierry Reding <thierry.reding@...onic-design.de>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"Nori, Sekhar" <nsekhar@...com>,
	"Hebbar, Gururaja" <gururaja.hebbar@...com>
Subject: RE: [PATCH 1/2] pwm: pwm-tiehrpwm: Low power sleep support

On Mon, Jan 14, 2013 at 12:38:56, Thierry Reding wrote:
> On Thu, Jan 10, 2013 at 06:33:43PM +0530, Philip Avinash wrote:
> [...]
> > diff --git a/drivers/pwm/pwm-tiehrpwm.c b/drivers/pwm/pwm-tiehrpwm.c
> [...]
> > +static int ehrpwm_pwm_suspend(struct device *dev)
> > +{
> > +	struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);
> > +
> > +	ehrpwm_pwm_context_save(pc);
> > +	pm_runtime_put_sync(dev);
> > +	return 0;
> > +}
> > +
> > +static int ehrpwm_pwm_resume(struct device *dev)
> > +{
> > +	struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);
> > +
> > +	pm_runtime_get_sync(dev);
> > +	ehrpwm_pwm_context_restore(pc);
> > +	return 0;
> > +}
> 
> According to Documentation/power/runtime_pm.txt, the PM core runs the
> pm_runtime_get_noresume() and pm_runtime_put_sync() before executing the
> .suspend() and .resume() callbacks. Are you sure you need to call them
> here explicitly?

I understand the problem of calling pm_runtime_get_sync() from .resume().
But this has to be called if pwm was running while going to suspend so that
pwm can continues to run after resume.

So I will add check of test_bit(PWMF_ENABLED, &pwm->flags) before 
pm_runtime_get/put_sync calls.

Thanks
Avinash

> 
> Thierry
> 

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