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

[Logan Gunthorpe <logang@deltatee.com>]

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.

> @@ -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@deltatee.com>