netdev - Re: 2.6.29-rc3: tg3 dead after resume

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Message-ID: <alpine.LFD.2.00.0901301541290.3150@localhost.localdomain>
Date:	Fri, 30 Jan 2009 15:51:17 -0800 (PST)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
cc:	Parag Warudkar <parag.lkml@...il.com>,
	Matt Carlson <mcarlson@...adcom.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: 2.6.29-rc3: tg3 dead after resume

On Sat, 31 Jan 2009, Rafael J. Wysocki wrote:
> 
> I wonder if this change makes any difference:
> 
> --- linux-2.6.orig/drivers/pci/pci-driver.c
> +++ linux-2.6/drivers/pci/pci-driver.c
> @@ -501,6 +501,9 @@ static int pci_pm_suspend(struct device
>  	if (pci_has_legacy_pm_support(pci_dev))
>  		return pci_legacy_suspend(dev, PMSG_SUSPEND);
>  
> +	if (!drv || !drv->pm)
> +		return 0;
> +
>  	if (drv && drv->pm && drv->pm->suspend) {
>  		error = drv->pm->suspend(dev);
>  		suspend_report_result(drv->pm->suspend, error);

I don't think that's right. Now you don't end up calling 
pci_pm_default_suspend_generic() at all, and this no pci_save_state().

But I think it could easily be the call to pci_disable_enabled_device(). 
It does that

	if (atomic_read(&dev->enable_cnt))
		do_pci_disable_device(dev);

and that ends up disabling PCI_COMMAND_MASTER and then calling 
pcibios_disable_device().

Any device we have ever done pci_enable_device() on would trigger this, 
which includes PCIE bridges, for example. And while the pcie driver does 
that

	pcie_portdrv_restore_config ->
		pci_enable_device(dev);

thing to re-enable it, that's a no-op since the enable_count is already 
non-zero.

And we do try to restore it (pci_restore_standard_config() will call 
pci_restore_state()), but since we've done the 
pci_disable_enabled_device() _before_ we did the pci_save_state(), we now 
restore a non-working setup. 

I think. The rules are too damn subtle there.  Rafael, can you look around 
a bit?

		Linus
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