Re: [PATCH v2 7/8] PCI: Add per-device MSI domain hook

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, Oct 06, 2015 at 06:04:02PM +0100, Marc Zyngier wrote:
> So far, we have considered that the MSI domain for a device was
> either set via the architecture-dependent pcibios implementation
> or inherited from the host bridge.
> 
> As we're about to break that assumption, add pci_dev_msi_domain
> which is the equivalent of pci_host_bridge_msi_domain, but for
> a single device.
> 
> Other than moving things around a bit, this patch on its own
> has no effect.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  drivers/pci/probe.c | 35 ++++++++++++++++++++++++++++++-----
>  1 file changed, 30 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 8361d27..7c333f8 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1622,15 +1622,40 @@ static void pci_init_capabilities(struct pci_dev *dev)
>  	pci_enable_acs(dev);
>  }
>  
> +/*
> + * This is the equivalent of pci_host_bridge_msi_domain that acts on
> + * devices. Firmware interfaces that can select the MSI domain on a
> + * per-device basis should be called from here.
> + */
> +static struct irq_domain *pci_dev_msi_domain(struct pci_dev *dev)
> +{
> +	struct irq_domain *d;
> +
> +	/*
> +	 * If a domain has been set through the pcibios_add_device
> +	 * callback, then this is the one (platform code knows best).
> +	 */
> +	d = dev_get_msi_domain(&dev->dev);
> +	if (d)
> +		return d;
> +
> +	return NULL;
> +}
> +
>  static void pci_set_msi_domain(struct pci_dev *dev)
>  {
> +	struct irq_domain *d;
> +
>  	/*
> -	 * If no domain has been set through the pcibios_add_device
> -	 * callback, inherit the default from the bus device.
> +	 * If the platform or firmware interfaces cannot supply a
> +	 * device-specific MSI domain, then inherit the default domain
> +	 * from the host bridge itself.
>  	 */
> -	if (!dev_get_msi_domain(&dev->dev))
> -		dev_set_msi_domain(&dev->dev,
> -				   dev_get_msi_domain(&dev->bus->dev));
> +	d = pci_dev_msi_domain(dev);
> +	if (!d)
> +		d = dev_get_msi_domain(&dev->bus->dev);
> +
> +	dev_set_msi_domain(&dev->dev, d);
>  }
>  
>  void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
> -- 
> 2.1.4
> 
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