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 12:34:07 -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 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?

-- 
Jesse Barnes, Intel Open Source Technology Center

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