Re: [PATCH RFC 1/2] PCI: Add controller reset method

On Mon, Aug 10, 2026 at 11:55:45AM -0700, Wei Liu wrote:
> Hi Bjorn,
> 
> Since this is adding to the PCI reset framework, this patch needs your
> approval.
> 
> Please see below for my questions. I'm happy to change the code however
> you see fit.
> 
> On Fri, Jul 24, 2026 at 04:08:42PM -0700, [email protected] wrote:
> > From: Wei Liu <[email protected]>
> > 
> > Some PCI controllers provide a function reset mechanism that is not
> > advertised in PCI configuration space. Allow them to expose it through an
> > optional pci_ops callback.
> > 
> > Add the controller reset method to the standard reset_method interface.
> > Prefer FLR and AF FLR by default, and use the controller operation before
> > PM and bus reset fallbacks.
> > 
> > Signed-off-by: Wei Liu <[email protected]>
> > ---
> >  drivers/pci/pci.c   | 22 ++++++++++++++++++++++
> >  include/linux/pci.h |  3 ++-
> >  2 files changed, 24 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 77b17b13ee61..4e55da202cad 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -4962,6 +4962,27 @@ static int pci_reset_bus_function(struct pci_dev *dev, bool probe)
> >  	return rc;
> >  }
> >  
> > +static int pci_controller_reset(struct pci_dev *dev, bool probe)
> > +{
> > +	int rc;
> > +
> > +	if (!dev->bus->ops->reset)
> > +		return -ENOTTY;
> > +
> > +	if (probe)
> > +		return dev->bus->ops->reset(dev, probe);
> > +
> > +	rc = pci_dev_reset_iommu_prepare(dev);
> > +	if (rc) {
> > +		pci_err(dev, "failed to stop IOMMU for a PCI reset: %d\n", rc);
> > +		return rc;
> > +	}
> > +
> > +	rc = dev->bus->ops->reset(dev, probe);
> > +	pci_dev_reset_iommu_done(dev);
> > +	return rc;
> > +}
> > +
> 
> The first question is whether modelling this on the controller level
> is the correct approach.
> 
> Please refer to the second patch for the intended usage in the Hyper-V
> vPCI code.
> 
> Whatever is added here, a new reset_method value will be added to the
> table. I chose "controller" to reflect the decision above.
> 

I recently added a hook for resetting the Root Ports in a platform specific way
[1]. This new hook is called in the SBR reset path. Will it work for you?

- Mani

[1] https://lore.kernel.org/all/[email protected]/

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