[PATCH v5 5/5] pci: Suspend iommu function prior to resetting a device

[Tian, Kevin]

> From: Nicolin Chen <nicolinc at nvidia.com>
> Sent: Tuesday, November 18, 2025 3:27 AM
> 
> On Mon, Nov 17, 2025 at 04:52:05AM +0000, Tian, Kevin wrote:
> > > From: Nicolin Chen <nicolinc at nvidia.com>
> > > Sent: Saturday, November 15, 2025 2:01 AM
> > >
> > > On Fri, Nov 14, 2025 at 09:45:31AM +0000, Tian, Kevin wrote:
> > > > > From: Nicolin Chen <nicolinc at nvidia.com>
> > > > > Sent: Tuesday, November 11, 2025 1:13 PM
> > > > >
> > > > > +/*
> > > > > + * Per PCIe r6.3, sec 10.3.1 IMPLEMENTATION NOTE, software
> disables
> > > ATS
> > > > > before
> > > > > + * initiating a reset. Notify the iommu driver that enabled ATS.
> > > > > + */
> > > > > +int pci_reset_iommu_prepare(struct pci_dev *dev)
> > > > > +{
> > > > > +	if (pci_ats_supported(dev))
> > > > > +		return iommu_dev_reset_prepare(&dev->dev);
> > > > > +	return 0;
> > > > > +}
> > > >
> > > > the comment says "driver that enabled ATS", but the code checks
> > > > whether ATS is supported.
> > > >
> > > > which one is desired?
> > >
> > > The comments says "the iommu driver that enabled ATS". It doesn't
> > > conflict with what the PCI core checks here?
> >
> > actually this is sent to all IOMMU drivers. there is no check on whether
> > a specific driver has enabled ATS in this path.
> 
> But the comment doesn't say "check"..
> 
> How about "Notify the iommu driver that enables/disables ATS"?
> 
> The point is that pci_enable_ats() is called in iommu drivers.
> 

but in current way even an iommu driver which doesn't call
pci_enable_ats() will also be notified then I didn't see the
point of adding an attribute to "the iommu driver".