linux-kernel - Re: [PATCH] gpio-intel-mid: fix the incorrect return of idle callback

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Date:	Tue, 28 Jan 2014 16:13:57 -0800
From:	David Cohen <david.a.cohen@...ux.intel.com>
To:	Felipe Balbi <balbi@...com>
Cc:	"xinhui.pan" <xinhuix.pan@...el.com>, linux-kernel@...r.kernel.org,
	linux-gpio@...r.kernel.org, linus.walleij@...aro.org,
	gnurou@...il.com, yanmin_zhang@...ux.intel.com
Subject: Re: [PATCH] gpio-intel-mid: fix the incorrect return of idle callback

On Tue, Jan 28, 2014 at 12:12:06PM -0600, Felipe Balbi wrote:
> On Tue, Jan 28, 2014 at 09:24:13AM -0800, David Cohen wrote:
> > On Tue, Jan 28, 2014 at 10:49:37AM -0600, Felipe Balbi wrote:
> > > On Tue, Jan 28, 2014 at 04:50:57PM +0800, xinhui.pan wrote:
> > > > From: "xinhui.pan" <xinhuiX.pan@...el.com>
> > > > 
> > > > intel_gpio_runtime_idle should return correct error code if it do fail.
> > > > make it more correct even though -EBUSY is the most possible return value.
> > > > 
> > > > Signed-off-by: bo.he <bo.he@...el.com>
> > > > Signed-off-by: xinhui.pan <xinhuiX.pan@...el.com>
> > > > ---
> > > >  drivers/gpio/gpio-intel-mid.c |    4 +++-
> > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/gpio/gpio-intel-mid.c b/drivers/gpio/gpio-intel-mid.c
> > > > index d1b50ef..05749a3 100644
> > > > --- a/drivers/gpio/gpio-intel-mid.c
> > > > +++ b/drivers/gpio/gpio-intel-mid.c
> > > > @@ -394,7 +394,9 @@ static const struct irq_domain_ops intel_gpio_irq_ops = {
> > > >  
> > > >  static int intel_gpio_runtime_idle(struct device *dev)
> > > >  {
> > > > -	pm_schedule_suspend(dev, 500);
> > > > +	int err = pm_schedule_suspend(dev, 500);
> > > > +	if (err)
> > > > +		return err;
> > > >  	return -EBUSY;
> > > 
> > > wait, is it only me or this would look a lot better as:
> > > 
> > > static int intel_gpio_runtime_idle(struct device *dev)
> > > {
> > > 	return pm_schedule_suspend(dev, 500);
> > > }
> > 
> > The reply to your suggestion is probably in this commit :)
> > 
> > ---
> > commit 45f0a85c8258741d11bda25c0a5669c06267204a
> > Author: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > Date:   Mon Jun 3 21:49:52 2013 +0200
> > 
> >     PM / Runtime: Rework the "runtime idle" helper routine
> > ---
> > 
> > We won't return 0 from here.
> 
> so you never want to return 0, why don't you, then:
> 
> static int intel_gpio_runtime_idle(struct device *dev)
> {
> 	pm_schedule_suspend(dev, 500);
> 	return -EBUSY;
> }

That's how it is currently :)

But this patch is making the function to return a different code in case
of error. IMHO there is not much fuctional gain with it, but I see
perhaps one extra info for tracing during development.

Anyway, I'll let Xinhui to do further comment since he's the author.

Br, David

> 
> just like drivers/tty/serial/mfd.c::serial_hsu_runtime_idle() is doing ?
> 
> -- 
> balbi


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