linux-kernel - Re: [BUGFIX 2/2] PCI/PM: Resume device before shutdown

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Message-ID: <CAErSpo7=6kCG=P-u_MOACD+HVV8cj1JLO-beZYr6tn9bOzfrBg@mail.gmail.com>
Date:	Sat, 3 Nov 2012 11:21:42 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Huang Ying <ying.huang@...el.com>
Cc:	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-pm@...r.kernel.org, "Rafael J. Wysocki" <rjw@...k.pl>
Subject: Re: [BUGFIX 2/2] PCI/PM: Resume device before shutdown

On Fri, Nov 2, 2012 at 11:05 PM, Huang Ying <ying.huang@...el.com> wrote:
> On Fri, 2012-11-02 at 10:52 -0600, Bjorn Helgaas wrote:
>> On Wed, Oct 24, 2012 at 12:54 AM, Huang Ying <ying.huang@...el.com> wrote:
>> > Some actions during shutdown need device to be in D0 state, such as
>> > MSI shutdown etc, so resume device before shutdown.
>>
>> Is there a problem report or bugzilla for this issue?  What are the
>> symptoms by which a user could figure out that he needs this fix?
>
> No bugzilla for this issue.  This issue will cause the corresponding
> device lost in kexeced kernel.

So would the following be accurate changelog text?

    Without this patch, a device may not work correctly after a kexec
    because the new kernel expects devices to be in D0.

>> Should this be put in the stable tree as well?  If so, for v3.6 only?

What about the stable tree?

>> > Signed-off-by: Huang Ying <ying.huang@...el.com>
>> > ---
>> >  drivers/pci/pci-driver.c |   12 ++----------
>> >  1 file changed, 2 insertions(+), 10 deletions(-)
>> >
>> > --- a/drivers/pci/pci-driver.c
>> > +++ b/drivers/pci/pci-driver.c
>> > @@ -398,6 +398,8 @@ static void pci_device_shutdown(struct d
>> >         struct pci_dev *pci_dev = to_pci_dev(dev);
>> >         struct pci_driver *drv = pci_dev->driver;
>> >
>> > +       pm_runtime_resume(dev);
>> > +
>> >         if (drv && drv->shutdown)
>> >                 drv->shutdown(pci_dev);
>> >         pci_msi_shutdown(pci_dev);
>> > @@ -408,16 +410,6 @@ static void pci_device_shutdown(struct d
>> >          * continue to do DMA
>> >          */
>> >         pci_disable_device(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
>
>
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