Re: [Qemu-devel] [RFC PATCH] vfio: add fixup for broken PCI devices

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Fri, 2012-05-25 at 06:24 -0600, Alex Williamson wrote:
> > > 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, 

Well, HW is HW ... it's going to be broken one way or another. Reset is
no exception, and we already have a way to deal with that sort of
breakage via the quirks. They are already divided in several categories
(early, normal, final, ...), I suggest we just add one for reset. No
point re-inventing a callback mechanism when we already have one.

Cheers,
Ben.