linux-kernel - Re: [PATCH v4 2/7] PCI/ATS: Initialize PRI in pci_ats

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Date:   Thu, 1 Aug 2019 15:09:29 -0600
From:   Keith Busch <kbusch@...nel.org>
To:     sathyanarayanan.kuppuswamy@...ux.intel.com
Cc:     bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, ashok.raj@...el.com,
        keith.busch@...el.com
Subject: Re: [PATCH v4 2/7] PCI/ATS: Initialize PRI in pci_ats_init()

On Wed, Jul 03, 2019 at 01:46:19PM -0700, sathyanarayanan.kuppuswamy@...ux.intel.com wrote:
> +#ifdef CONFIG_PCI_PRI
> +static void pci_pri_init(struct pci_dev *pdev)
> +{
> +	u32 max_requests;
> +	int pos;
> +
> +	/*
> +	 * As per PCIe r4.0, sec 9.3.7.11, only PF is permitted to
> +	 * implement PRI and all associated VFs can only use it.
> +	 * Since PF already initialized the PRI parameters there is
> +	 * no need to proceed further.
> +	 */
> +	if (pdev->is_virtfn)
> +		return;
> +
> +	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
> +	if (!pos)
> +		return;
> +
> +	pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests);
> +
> +	/*
> +	 * Since PRI is a shared resource between PF and VF, we must not
> +	 * configure Outstanding Page Allocation Quota as a per device
> +	 * resource in pci_enable_pri(). So use maximum value possible
> +	 * as default value.
> +	 */
> +	pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, max_requests);
> +
> +	pdev->pri_reqs_alloc = max_requests;
> +	pdev->pri_cap = pos;
> +}
> +#endif
> +
>  void pci_ats_init(struct pci_dev *dev)
>  {
>  	int pos;
> @@ -28,6 +62,10 @@ void pci_ats_init(struct pci_dev *dev)
>  		return;
>  
>  	dev->ats_cap = pos;
> +
> +#ifdef CONFIG_PCI_PRI
> +	pci_pri_init(dev);
> +#endif
>  }

Rather than surround the call to pci_pri_init() with the #ifdef, you
should provide an empty function implementation when CONFIG_PCI_PRI is
not defined. Same thing for the next patch adding PASID.