linux-kernel - Re: [PATCH] PCI / ACPI: Always resume devices on ACPI wakeup notifications

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Date:	Mon, 25 Mar 2013 23:34:59 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Sarah Sharp <sarah.a.sharp@...ux.intel.com>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Len Brown <lenb@...nel.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	"Accardi, Kristen C" <kristen.c.accardi@...el.com>,
	"Huang, Ying" <ying.huang@...el.com>, linux-pci@...r.kernel.org
Subject: Re: [PATCH] PCI / ACPI: Always resume devices on ACPI wakeup notifications

On Monday, March 25, 2013 09:45:51 AM Sarah Sharp wrote:
> On Sat, Mar 23, 2013 at 03:33:03PM +0100, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > 
> > It turns out that _Lxx control methods provided by some BIOSes clear
> > the PME Status bit of PCI devices they handle, which means that
> > pci_acpi_wake_dev() cannot really use that bit to check whether or
> > not the device has signalled wakeup.
> > 
> > For this reason, make pci_acpi_wake_dev() always attempt to resume
> > the device it is called for regardless of the device's PME Status bit
> > value (that bit still has to be cleared if set at this point,
> > though).
> > 
> > Reported-by: Sarah Sharp <sarah.a.sharp@...ux.intel.com>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Should this be marked for stable?  I had this issue on 3.7 and 3.8 as
> well.

Yes, it probably should, but that's the maintainer's call.

Thanks,
Rafael


> > ---
> >  drivers/pci/pci-acpi.c |   15 ++++++++-------
> >  1 file changed, 8 insertions(+), 7 deletions(-)
> > 
> > Index: linux-pm/drivers/pci/pci-acpi.c
> > ===================================================================
> > --- linux-pm.orig/drivers/pci/pci-acpi.c
> > +++ linux-pm/drivers/pci/pci-acpi.c
> > @@ -53,14 +53,15 @@ static void pci_acpi_wake_dev(acpi_handl
> >  		return;
> >  	}
> >  
> > -	if (!pci_dev->pm_cap || !pci_dev->pme_support
> > -	     || pci_check_pme_status(pci_dev)) {
> > -		if (pci_dev->pme_poll)
> > -			pci_dev->pme_poll = false;
> > +	/* Clear PME Status if set. */
> > +	if (pci_dev->pme_support)
> > +		pci_check_pme_status(pci_dev);
> >  
> > -		pci_wakeup_event(pci_dev);
> > -		pm_runtime_resume(&pci_dev->dev);
> > -	}
> > +	if (pci_dev->pme_poll)
> > +		pci_dev->pme_poll = false;
> > +
> > +	pci_wakeup_event(pci_dev);
> > +	pm_runtime_resume(&pci_dev->dev);
> >  
> >  	if (pci_dev->subordinate)
> >  		pci_pme_wakeup_bus(pci_dev->subordinate);
> > 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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