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Message-ID: <1337948650.4714.88.camel@ul30vt>
From: Alex Williamson <alex.williamson@redhat.com>
Date: Fri, 25 May 2012 06:24:10 -0600
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References: <4FBF3627.3030504@ozlabs.ru> <1337934518.16119.15.camel@pasglop>
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Subject: Re: [Qemu-devel] [RFC PATCH] vfio: add fixup for broken PCI devices
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To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>, qemu-devel@nongnu.org, Alex Graf <agraf@suse.de>, kvm@vger.kernel.org, David Gibson <david@gibson.dropbear.id.au>

On Fri, 2012-05-25 at 18:28 +1000, Benjamin Herrenschmidt wrote:
> On Fri, 2012-05-25 at 17:35 +1000, Alexey Kardashevskiy wrote:
> > Some adapters (like NEC PCI USB controller) do not flush their config
> > on a sioftware reset and remember DMA config, etc.
> > 
> > If we use such an adapter with QEMU, then crash QEMU (stop it with
> > ctrl-A ctrl-X), and try to use it in QEMU again, it may start working
> > immediately with previous config when pci_enable_device() is called
> > on that PCI function.
> > 
> > To eliminate such effect, some quirk should be called. The proposed
> > pci_fixup_final does its job well for mentioned NEC PCI USB but not
> > sure if it is 100% correct.
> 
> I think we should create a new quirk category... call it pci_fixup_reset
> or something like that, which is responsible for blasting the thing into
> submission when ownership changes.
> 
> We'll need these for more than just USB I suspect.

We already have pci_dev_specific_reset() called from pci_dev_reset().
Does this device support any of the standard reset mechanisms?  It would
be nice to know what within the final fixups keeps this device working.
Thanks,

Alex