Re: [PATCH 1/2] PCI: Add pci_ops.add_bus() callback

[Bjorn Helgaas <helgaas@kernel.org>]

Hi Thierry,

On Mon, Nov 23, 2015 at 01:40:25PM +0100, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> This callback will be called on every newly created bus. Drivers can
> implement it to perform driver-specific initialization of the bus.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  drivers/pci/probe.c | 8 +++++++-
>  include/linux/pci.h | 1 +
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index e735c728e3b3..fbed432f8915 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -754,7 +754,13 @@ add_dev:
>  	ret = device_register(&child->dev);
>  	WARN_ON(ret < 0);
>  
> -	pcibios_add_bus(child);
> +	if (child->ops->add_bus) {
> +		ret = child->ops->add_bus(child);
> +		if (ret < 0)
> +			dev_err(&child->dev, "failed to add bus: %d\n", ret);
> +	} else {
> +		pcibios_add_bus(child);
> +	}

pcibios_add_bus() does arch-specific things.  child->ops->add_bus()
does driver-specific things.  I think these are orthogonal, so I think
we want to *always* call pcibios_add_bus(), don't we?

>  	/* Create legacy_io and legacy_mem files for this bus */
>  	pci_create_legacy_files(child);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index e828e7b4afec..70c1228d585f 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -569,6 +569,7 @@ static inline int pcibios_err_to_errno(int err)
>  /* Low-level architecture-dependent routines */
>  
>  struct pci_ops {
> +	int (*add_bus)(struct pci_bus *bus);
>  	void __iomem *(*map_bus)(struct pci_bus *bus, unsigned int devfn, int where);
>  	int (*read)(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 *val);
>  	int (*write)(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 val);
> -- 
> 2.5.0
> 
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