Re: [PATCH 10/13] PCI/P2PDMA: Extract pure ACS routing decision helpers

[Leon Romanovsky]

On Tue, Aug 04, 2026 at 04:07:27PM -0600, Logan Gunthorpe wrote:
> 
> 
> On 2026-08-02 09:09, Leon Romanovsky wrote:
> 
> >  static enum pci_acs_p2pdma_state
> >  pci_acs_p2pdma_state(struct pci_dev *pdev, struct pci_dev *target)
> >  {
> > -	int pos, ret;
> > +	int egress = 0;
> >  	u16 ctrl;
> >  
> > -	pos = pdev->acs_cap;
> > -	if (!pos)
> > +	if (!pdev->acs_cap)
> >  		return PCI_ACS_P2PDMA_DIRECT;
> 
> I don't necessarily disagree with the change, but removing pos in this
> patch seems unnecessary and makes the patch more difficult to review
> than it needed to be.

I usually combine small cleanups, but I'll restore pos here in
the next version if I repost this patch.

> 
> > @@ -1046,6 +1047,22 @@ resource_size_t pci_min_window_alignment(struct pci_bus *bus,
> >  void pci_acs_init(struct pci_dev *dev);
> >  void pci_enable_acs(struct pci_dev *dev);
> >  int pci_acs_egress_ctrl_set(struct pci_dev *pdev, struct pci_dev *target);
> > +
> > +/*
> > + * Peer-to-peer routing decision for an ACS-capable ingress port, per
> > + * PCIe r7.0, sec 6.12.3, table 6-11.
> > + */
> > +enum pci_acs_p2pdma_state {
> > +	PCI_ACS_P2PDMA_DIRECT,		/* peer-to-peer permitted directly */
> > +	PCI_ACS_P2PDMA_REDIRECT,	/* redirected upstream to host bridge */
> > +	PCI_ACS_P2PDMA_NOT_SUPPORTED,	/* no usable peer-to-peer route */
> > +};
> > +
> > +#if IS_ENABLED(CONFIG_KUNIT)
> > +bool pci_acs_egress_port_valid(u16 acs_caps, u8 target_port);
> > +enum pci_acs_p2pdma_state pci_acs_p2pdma_decision(u16 ctrl, bool has_target,
> > +						  int egress);
> > +#endif
> 
> One minor weird whitespace issue here. Probably the empty line should
> come after #endif
> 
> 
> But both of these are very minor points, so:
> 
> Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>

Thanks

> 
> 
>