On Mon, Jul 16, 2012 at 11:30:27PM +0800, Gavin Shan wrote:
> The patch implements the weak function to return the default I/O
> or memory alignment for P2P bridge. Currently, I/O window has 4KiB
> alignment and memory window is 4MiB aligned by default. On the other
> hand, those platforms (e.g. powernv) that have special requirements
> on the alignment could override the function by themselves.
>
> Signed-off-by: Gavin Shan <shangw@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/pci/host-bridge.c | 17 +++++++++++++++++
> include/linux/pci.h | 2 ++
> 2 files changed, 19 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> index abcf053..dcbc47d 100644
> --- a/drivers/pci/host-bridge.c
> +++ b/drivers/pci/host-bridge.c
> @@ -105,3 +105,20 @@ void pcibios_bus_to_resource(struct pci_dev *dev, struct resource *res,
> }
>
> EXPORT_SYMBOL(pcibios_bus_to_resource);
> +
> +/*
> + * Retrieve the default memory or I/O alignment for the
> + * specific P2P bridge. The function has been implemented
> + * as weak so that it can be overrided by platform that
> + * has special requirments for memory and I/O alignment.
> + */
> +resource_size_t __weak pcibios_window_alignment(struct pci_bus *bus,
> + unsigned long type)
This no longer has anything to do with the host bridge, so I think it
could be moved to setup-bus.c and made static. We shouldn't have to
repeat the default 1M and 4K code in the arch versions, so maybe we
could do something like this:
resource_size_t __weak pcibios_window_alignment(struct pci_bus *bus, unsigned long type)
{
return 1;
}
static resource_size_t window_alignment(struct pci_bus *bus, unsigned long type)
{
resource_size_t align = 1, arch_align;
if (type & IORESOURCE_MEM)
align = 1024*1024;
else if (type & IORESOURCE_IO)
align = 4*1024;
arch_align = pcibios_window_alignment(bus, type);
return max(align, arch_align);
}
I made the default 1, thinking of bus number apertures (though we don't use this
path for bus numbers today).
> +{
> + /* Memory windows must be 1MiB aligned */
> + if (type & IORESOURCE_MEM)
> + return 1024*1024;
> +
> + /* I/O windows have default alignment of 4KiB */
> + return 4*1024;
> +}
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 9acea4b..283da11 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -662,6 +662,8 @@ void __pcibios_bus_to_resource(struct pci_bus *bus, struct resource *res,
> struct pci_bus_region *region);
> void pcibios_bus_to_resource(struct pci_dev *dev, struct resource *res,
> struct pci_bus_region *region);
> +resource_size_t pcibios_window_alignment(struct pci_bus *bus,
> + unsigned long type);
> void pcibios_scan_specific_bus(int busn);
> extern struct pci_bus *pci_find_bus(int domain, int busnr);
> void pci_bus_add_devices(const struct pci_bus *bus);
> --
> 1.7.5.4
>
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