linux-kernel - Re: [PATCH] PCI / PM: Disable wakeup during shutdown for devices not enabled to wake up

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Date:	Fri, 10 Feb 2012 15:51:45 -0800
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Linux PM list <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org,
	Alan Stern <stern@...land.harvard.edu>
Subject: Re: [PATCH] PCI / PM: Disable wakeup during shutdown for devices
 not enabled to wake up

On Fri, 10 Feb 2012 23:40:29 +0100
"Rafael J. Wysocki" <rjw@...k.pl> wrote:

> On Friday, February 10, 2012, Jesse Barnes wrote:
> > On Tue, 7 Feb 2012 00:50:35 +0100
> > "Rafael J. Wysocki" <rjw@...k.pl> wrote:
> > 
> > > From: Rafael J. Wysocki <rjw@...k.pl>
> > > 
> > > If a PCI device is enabled to generate wakeup signals (PME) when put
> > > into a low-power state by runtime PM, it will be still enabled to
> > > generate those signals after the system shutdown, unless its driver's
> > > .shutdown() callback takes care of the wakeup signals generation
> > > setting.  Moreover, there are devices that are not enabled to wake
> > > up the system and that are configured by runtime PM to generate
> > > wakeup signals so that (runtime) remote wakeup works with them.
> > > Those devices should be reconfigured during system shutdown so that
> > > they don't generate wakeup signals, but at least some drivers don't
> > > do that.  However, that very well may be done by the PCI core so
> > > that drivers don't have to worry about it.  For this reason, modify
> > > pci_device_shutdown() to disable the generation of wakeup events for
> > > devices not supposed to wake up the system.
> > > 
> > > References: https://bugzilla.kernel.org/show_bug.cgi?id=37952
> > > Reported-and-tested-by: Kamil Iskra <kamil.54002@...ra.name>
> > > Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> > > ---
> > >  drivers/pci/pci-driver.c |   10 ++++++++++
> > >  1 file changed, 10 insertions(+)
> > > 
> > > Index: linux/drivers/pci/pci-driver.c
> > > ===================================================================
> > > --- linux.orig/drivers/pci/pci-driver.c
> > > +++ linux/drivers/pci/pci-driver.c
> > > @@ -430,6 +430,16 @@ static void pci_device_shutdown(struct d
> > >  		drv->shutdown(pci_dev);
> > >  	pci_msi_shutdown(pci_dev);
> > >  	pci_msix_shutdown(pci_dev);
> > > +
> > > +	/*
> > > +	 * Devices may be enabled to wake up by runtime PM, but they need not
> > > +	 * be supposed to wake up the system from its "power off" state (e.g.
> > > +	 * ACPI S5).  Therefore disable wakeup for all devices that aren't
> > > +	 * supposed to wake up the system at this point.  The state argument
> > > +	 * will be ignored by pci_enable_wake().
> > > +	 */
> > > +	if (!device_may_wakeup(dev))
> > > +		pci_enable_wake(pci_dev, PCI_UNKNOWN, false);
> > >  }
> > >  
> > >  #ifdef CONFIG_PM
> > > 
> > 
> > So where do we end up setting the right wakeup state for devices we
> > actually *do* want to wake the system from S5?  Presumably later in the
> > shutdown sequence?
> 
> Yes, in general.  However, device_may_wakeup(dev) has to return true for those
> devices, so they aren't affected by this change.

Ok thanks Rafael, applied.  Now to do a little testing...

Thanks,
-- 
Jesse Barnes, Intel Open Source Technology Center

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