From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: Suspend problems in 2.6.31-rc6
Date: Thu, 20 Aug 2009 17:34:28 +0200
Message-ID: <200908201734.28331.rjw@sisk.pl>
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To: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Greg KH <greg@kroah.com>, Jesse Barnes <jbarnes@virtuousgeek.org>, Dave Airlie <airlied@redhat.com>, Linux-pm mailing list <linux-pm@lists.linux-foundation.org>, Alan Cox <alan@lxorguk.ukuu.org.uk>
List-Id: linux-pm@vger.kernel.org

On Thursday 20 August 2009, Zhenyu Wang wrote:
> On 2009.08.19 10:42:07 -0400, Alan Stern wrote:
> > On Wed, 19 Aug 2009, Zhenyu Wang wrote:
> > 
> > > Rafael, as I added this restore long time ago, pci core has changed in some way?
> > > We had problem when reconfigure agp GTT space in resume, as we must be sure
> > > gfx device's config space has been restored properly, and as 02:00 gfx device
> > > restored later than host bridge 00:00 device, that came to my origin patch to
> > > restore it earlier.
> > 
> > Why did you do it that way?  I mean, why not restore the gfx device's 
> > config space in its own resume routine instead of in the host bridge's 
> > resume routine?
> > 
> 
> That's the order issue I have mentioned. intel_agp is the pci driver for
> host bridge (dev 00:00), and drm/i915 is the pci driver for gfx device
> (dev 00:02). Host bridge will always resume earlier than gfx device, but
> for intel_agp we need to access gfx device when reconfigure GTT in resume,
> we can't wait until restore happen in i915 driver.
> 
> So there might be a conflict here, as i915 driver also do pci_restore_state()
> after we did reconfigure in intel_agp driver, some configs may be corrupted 
> then. Although I haven't seen it in real testing. 

I think that shouldn't be a problem any more in the 2.6.29 and later kernels,
because the PCI standard config registers are now restored by the PCI bus
code at the early resume stage.

Thanks,
Rafael