linux-kernel - Re: [PATCH] pci/runtime-pm: respect devices autosuspend timeout on config access

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Date:	Wed, 07 Nov 2012 14:26:25 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	David Airlie <airlied@...hat.com>
Cc:	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Subject: Re: [PATCH] pci/runtime-pm: respect devices autosuspend timeout on
 config access

On Wed, 2012-11-07 at 01:15 -0500, David Airlie wrote:
> > > 
> > > Cc: Huang Ying <ying.huang@...el.com>
> > > Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> > > Cc: Rafael J. Wysocki <rjw@...k.pl>
> > > Signed-off-by: Dave Airlie <airlied@...hat.com>
> > > ---
> > >  drivers/pci/pci-sysfs.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> > > index 02d107b..12d3d52 100644
> > > --- a/drivers/pci/pci-sysfs.c
> > > +++ b/drivers/pci/pci-sysfs.c
> > > @@ -487,7 +487,7 @@ pci_config_pm_runtime_put(struct pci_dev *pdev)
> > >  	struct device *dev = &pdev->dev;
> > >  	struct device *parent = dev->parent;
> > >  
> > > -	pm_runtime_put(dev);
> > > +	pm_runtime_put_autosuspend(dev);
> > >  	if (parent)
> > >  		pm_runtime_put_sync(parent);
> > >  }
> > 
> > I think you do not need that.  You can implement timeout
> > in .runtime_idle callback of the driver.
> 
> If I understand what you are suggesting, I should setup some kinda of timer callback to later call suspend, but that seems pointless for me if we have the autosuspend mechanism in place.
> 
> Won't I end up racing my timer against other pm stuff? I'm not really runtime pm expert so maybe I'm just missing something.

You can call pm_runtime_autosuspend or pm_runtime_schedule_suspend
in .runtime_idle callback of the driver.

Best Regards,
Huang Ying


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