Re: [PATCH v5 02/18] PCI/CXL: Probe the underlying bus reset in cxl_reset_bus_function()

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, Aug 27, 2026 at 01:49:05PM -0700, Nicolin Chen wrote:
> On Thu, Aug 27, 2026 at 05:31:31PM -0300, Jason Gunthorpe wrote:
> > > [ ... 27 lines skipped ... ]
> > > @@ -4979,8 +4979,16 @@ static int cxl_reset_bus_function(struct pci_dev *dev, bool probe)
> > >  	if (!dvsec)
> > >  		return -ENOTTY;
> > >  
> > > -	if (probe)
> > > -		return 0;
> > > +	/*
> > > +	 * Do not probe via pci_reset_bus_function(), which would reject a
> > > +	 * masked SBR that the do-reset path below unmasks before resetting.
> > > +	 */
> > > +	if (probe) {
> > > +		rc = pci_dev_reset_slot_function(dev, PCI_RESET_PROBE);
> > > +		if (rc != -ENOTTY)
> > > +			return rc;
> > > +		return pci_parent_bus_reset(dev, PCI_RESET_PROBE);
> > > +	}
> > 
> > Why not put this a little lower after the:
> > 
> > >
> > >  	rc = pci_read_config_word(bridge, dvsec + PCI_DVSEC_CXL_PORT_CTL, &reg);
> > >  	if (rc)
> > 
> > ?
> 
> Hmm, the "if (probe)" was checked before pci_read_config_word, so I
> kept it there. I don't quite get the reason of putting it behind.
> 
> Mind elaborating?

I'm looking at the ENOTTY:

	rc = pci_read_config_word(bridge, dvsec + PCI_DVSEC_CXL_PORT_CTL, &reg);
	if (rc)
		return -ENOTTY;

If the general point with these fixes was probe should capture all the
ENOTTY cases under probe there should not be an ENOTTY return outside
probe.

So maybe that should be ENODEV, or maybe probe should check it. I'm
not really sure how config read can fail, so maybe ENODEV is the right
direction

Jason