linux-kernel - Re: [PATCH] PM / Domains: Propagate start and restore errors during runtime resume

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Date:	Fri, 04 Mar 2016 22:38:59 +0200
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Ulf Hansson <ulf.hansson@...aro.org>
Cc:	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Kevin Hilman <khilman@...nel.org>
Subject: Re: [PATCH] PM / Domains: Propagate start and restore errors during runtime resume

Hi Ulf,

Thank you for the review.

On Friday 04 March 2016 11:22:49 Ulf Hansson wrote:
> On 2 March 2016 at 00:20, Laurent Pinchart wrote:
> > During runtime resume the return values of the start and restore steps
> > are ignored. As a result drivers are not notified of runtime resume
> > failures and can't propagate them up. Fix it by returning an error if
> > either the start or restore step fails, and clean up properly in the
> > error path.
> > 
> > Signed-off-by: Laurent Pinchart
> > <laurent.pinchart+renesas@...asonboard.com>
> > ---
> > 
> >  drivers/base/power/domain.c | 20 ++++++++++++++++++--
> >  1 file changed, 18 insertions(+), 2 deletions(-)
> > 
> > This fixes an issue I've noticed with my driver's .runtime_resume()
> > handler returning an error that was never propagated out of
> > pm_runtime_get_sync().
> > 
> > A second issue then appeared. The device .runtime_error field is set to
> > the error code returned by my .runtime_resume() handler, but it never
> > reset. Any subsequent try to resume the device fails with -EINVAL. I'm not
> > sure what the right way to solve that is, advices are welcome.
> > 
> > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> > index 301b785f9f56..8cfcb8d6179b 100644
> > --- a/drivers/base/power/domain.c
> > +++ b/drivers/base/power/domain.c
> > @@ -485,8 +485,13 @@ static int pm_genpd_runtime_resume(struct device
> > *dev)
> >         if (timed && runtime_pm)
> >                 time_start = ktime_get();
> > 
> > -       genpd_start_dev(genpd, dev);
> > -       genpd_restore_dev(genpd, dev);
> > +       ret = genpd_start_dev(genpd, dev);
> > +       if (ret)
> > +               goto err_poweroff;
> > +
> > +       ret = genpd_restore_dev(genpd, dev);
> > +       if (ret)
> > +               goto err_stop;
> > 
> >         /* Update resume latency value if the measured time exceeds it. */
> >         if (timed && runtime_pm) {
> > @@ -501,6 +506,17 @@ static int pm_genpd_runtime_resume(struct device
> > *dev)
> >         }
> >         
> >         return 0;
> > +
> > +err_stop:
> > +       genpd_stop_dev(genpd, dev);
> > +err_poweroff:
> > +       if (!dev->power.irq_safe) {
> 
> There's a helper function for this:
> pm_runtime_is_irq_safe()
> 
> Perhaps, we can leave this as is here and then make a separate patch
> converting all occurrences of the above into using the helper function
> instead.

If there are other occurrences a separate patch would make sense, I agree.

> > +               mutex_lock(&genpd->lock);
> > +               genpd_poweroff(genpd, 0);
> > +               mutex_unlock(&genpd->lock);
> > +       }
> > +
> > +       return ret;
> > 
> >  }
> >  
> >  static bool pd_ignore_unused;
> 
> Acked-by: Ulf Hansson <ulf.hansson@...aro.org>

Thank you. Do you plan to take the patch in your tree for v4.6 ?

-- 
Regards,

Laurent Pinchart