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Date:	Sun, 8 Mar 2009 23:57:17 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Jesse Brandeburg <jesse.brandeburg@...il.com>,
	David Miller <davem@...emloft.net>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	NetDev <netdev@...r.kernel.org>
Subject: Re: [PATCH] igb: fix kexec with igb

On Sunday 08 March 2009, Yinghai Lu wrote:
> On Sun, Mar 8, 2009 at 2:32 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > On Sunday 08 March 2009, Rafael J. Wysocki wrote:
> >> On Sunday 08 March 2009, Yinghai Lu wrote:
> >> > Rafael J. Wysocki wrote:
> >> > > On Saturday 07 March 2009, Yinghai Lu wrote:
> >> > >> On Fri, Mar 6, 2009 at 11:18 PM, Jesse Brandeburg
> >> > >> <jesse.brandeburg@...il.com> wrote:
> >> > >>> On Fri, Mar 6, 2009 at 8:33 PM, Yinghai Lu <yinghai@...nel.org> wrote:
> >> > >>>> Impact: could probe igb
> >> > >>>>
> >> > >>>> Found one system with 82575EB, in the kernel that is kexeced, probe igb
> >> > >>>> failed with -2.
> >> > >>>>
> >> > >>>> it looks like the same behavior happened on forcedeth.
> >> > >>>>
> >> > >>>> try to check system_state to make sure if put it on D3
> >> > >>>>
> >> > >>>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> >> > >>>>
> >> > >>>> ---
> >> > >>>>  drivers/net/igb/igb_main.c |   19 ++++++++++++++-----
> >> > >>>>  1 file changed, 14 insertions(+), 5 deletions(-)
> >> > >>> I see the point of the patch, but I know for a fact that ixgbe when
> >> > >>> enabled for MSI-X also doesn't work with kexec.
> >> > >>>
> >> > >>> so my questions are:
> >> > >>> are you going to change every driver?
> >> > >> i tend to only change driver that i have related HW.
> >> > >>
> >> > >>> why can't this be fixed in core kernel code instead?
> >> > >> will check it.
> >> > >>
> >> > >>> Shouldn't pci_enable_device take it out of D3?
> >> > >>> Or maybe it should be taken out of D3 immediately if someone tries to
> >> > >>> ioremap any of the BARx registers?
> >> > >>
> >> > >> looks like second kernel can not detect the state any more.
> >> > >
> >> > > In fact pci_enable_device() calls pci_set_power_state(dev, PCI_D0) as the first
> >> > > thing.  The question is why it doesn't work as expected.
> >> >
> >> > not sure... please check the version for forcedeth that you made.
> >> >
> >> > commit 3cb5599a84c557c0dd9a19feb63a3788268cf249
> >> > Author: Rafael J. Wysocki <rjw@...k.pl>
> >> > Date:   Fri Sep 5 14:00:19 2008 -0700
> >> >
> >> >     forcedeth: fix kexec regression
> >> >
> >> >     Fix regression tracked as http://bugzilla.kernel.org/show_bug.cgi?id=11361
> >> >     and caused by commit f735a2a1a4f2a0f5cd823ce323e82675990469e2 ("[netdrvr]
> >> >     forcedeth: setup wake-on-lan before shutting down") that makes network
> >> >     adapters integrated into the NVidia MCP55 chipsets fail to work in kexeced
> >> >     kernels.  The problem appears to be that if the adapter is put into D3_hot
> >> >     during ->shutdown(), it cannot be brought back into D0 after kexec (ref.
> >> >     http://marc.info/?l=linux-kernel&m=121900062814967&w=4).  Therefore, only
> >> >     put forcedeth into D3 during ->shutdown() if the system is to be powered
> >> >     off.
> >>
> >> Thanks, I remember now.
> >
> > In which case you need to rework igb_shutdown() rather than igb_suspend().
> >
> > Something like the patch below, perhaps (totally untested).
> >
> > Thanks,
> > Rafael
> >
> > ---
> >  drivers/net/igb/igb_main.c |   24 +++++++++++++++++++-----
> >  1 file changed, 19 insertions(+), 5 deletions(-)
> >
> > Index: linux-2.6/drivers/net/igb/igb_main.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/net/igb/igb_main.c
> > +++ linux-2.6/drivers/net/igb/igb_main.c
> > @@ -4299,7 +4299,7 @@ int igb_set_spd_dplx(struct igb_adapter
> >  }
> >
> >
> > -static int igb_suspend(struct pci_dev *pdev, pm_message_t state)
> > +static int __igb_shutdown(struct pci_dev *pdev, bool enable_wake)
> >  {
> >        struct net_device *netdev = pci_get_drvdata(pdev);
> >        struct igb_adapter *adapter = netdev_priv(netdev);
> > @@ -4359,7 +4359,7 @@ static int igb_suspend(struct pci_dev *p
> >        }
> >
> >        /* make sure adapter isn't asleep if manageability/wol is enabled */
> > -       if (wufc || adapter->en_mng_pt) {
> > +       if ((wufc || adapter->en_mng_pt) && enable_wake) {
> >                pci_enable_wake(pdev, PCI_D3hot, 1);
> >                pci_enable_wake(pdev, PCI_D3cold, 1);
> >        } else {
> > @@ -4374,12 +4374,21 @@ static int igb_suspend(struct pci_dev *p
> >
> >        pci_disable_device(pdev);
> >
> > -       pci_set_power_state(pdev, pci_choose_state(pdev, state));
> > -
> >        return 0;
> >  }
> >
> >  #ifdef CONFIG_PM
> > +static int igb_suspend(struct pci_dev *pdev, pm_message_t state)
> > +{
> > +       int retval;
> > +
> > +       retval = __igb_shutdown(pdev, true);
> > +       if (!retval)
> > +               pci_set_power_state(pdev, PCI_D3hot);
> > +
> > +       return retval;
> > +}
> > +
> >  static int igb_resume(struct pci_dev *pdev)
> >  {
> >        struct net_device *netdev = pci_get_drvdata(pdev);
> > @@ -4434,7 +4443,12 @@ static int igb_resume(struct pci_dev *pd
> >
> >  static void igb_shutdown(struct pci_dev *pdev)
> >  {
> > -       igb_suspend(pdev, PMSG_SUSPEND);
> > +       if (system_state == SYSTEM_POWER_OFF) {
> > +               __igb_shutdown(pdev, true);
> > +               pci_set_power_state(pdev, PCI_D3hot);
> 
> you don't need to use pci_choose_state(pdev, state), but use PCI-D3hot directly?

Yes, because we've already decided we'd put the device into D3_hot by calling
pci_enable_wake(pdev, PCI_D3hot, 1) in __igb_shutdown().

In fact we should first determine the target state and _then_ call
pci_enable_wake() and pci_set_power_state() with that as the argument, but this
is a separate issue.  For now, IMO, it's better to use D3_hot in both places
directly.

On a slightly related note, the sequence

                pci_enable_wake(pdev, PCI_D3hot, 1);
                pci_enable_wake(pdev, PCI_D3cold, 1);

is (slightly) incorrect by itself, because ACPI doesn't distinguish bewteen
D3_hot and D3_cold, so this just causes the same platform code to run twice,
which may or may not work (it theory it should always work, but still).

This is yet another problem, though.

Thanks,
Rafael
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