linux-kernel - Re: [Bug #14730] sky2 won't work after suspend/resume cycle

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Message-Id: <200912292341.56040.rjw@sisk.pl>
Date:	Tue, 29 Dec 2009 23:41:55 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Kernel Testers List <kernel-testers@...r.kernel.org>,
	"Maciej J. Woloszyk" <mat@....com.pl>
Subject: Re: [Bug #14730] sky2 won't work after suspend/resume cycle

On Tuesday 29 December 2009, OGAWA Hirofumi wrote:
> "Rafael J. Wysocki" <rjw@...k.pl> writes:
> 
> > On Tuesday 29 December 2009, OGAWA Hirofumi wrote:
> >> "Rafael J. Wysocki" <rjw@...k.pl> writes:
> >> 
> >> > This message has been generated automatically as a part of a report
> >> > of regressions introduced between 2.6.31 and 2.6.32.
> >> >
> >> > The following bug entry is on the current list of known regressions
> >> > introduced between 2.6.31 and 2.6.32.  Please verify if it still should
> >> > be listed and let me know (either way).
> >> >
> >> >
> >> > Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=14730
> >> > Subject		: sky2 won't work after suspend/resume cycle
> >> > Submitter	: Maciej J. Woloszyk <mat@....com.pl>
> >> > Date		: 2009-12-04 09:02 (26 days old)
> >> 
> >> This seems to be related to commit 4b77b0a2ba27d64f58f16d8d4d48d8319dda36ff.
> >> 
> >> It clears dev->state_saved blindly, but pci_pm_resume() calls
> >> pci_restore_standard_config() before pm->resume() (by probably
> >> historical reason).
> >
> > The other way around.  pci_restore_standard_config() is the new thing and the
> > pci_restore_state() in ->resume() is supposed to be unnecessary.  Unfortunately
> > in this case the restoration of PCI config registers in
> > pci_restore_standard_config() doesn't work.
> >
> > I'd like to understand the reason, but temporarily we can just set
> > pdev->state_saved to 1 in sky2_resume(), as proposed in the bug entry.
> 
> Sure. However, it might not be only sky2.

That's correct.  It more likely is a chipset issue.

> Well, anyway, another likely one is - restore() should be called after
> pci_pm_default_resume()?

No, because we want the PCI standard config spaces to be restored before
the device interrupts are enabled to avoid intermittent resume failures related
to interrupt mishandling.

That's why it is important to understand the nature of the sky2 failure here.

Rafael
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