Re: PCI resource problems caused by improper address rounding

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 20 Dec 2007 11:46:16 +0300 Ivan Kokshaysky <ink@jurassic.park.msu.ru> wrote:

> PCI: do respect full 64-bit address for bridge prefetch window
> 
> Prevent the prefetch window from being programmed with a bogus address
> when its respective resource gets allocated above the 4G mark.
> 
> Note that we cannot yet guarantee correct resource allocations
> above 4G, though it might work in some simple cases.
> 

So.. did we agree that this patch is good to go?

> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -208,8 +208,11 @@ pci_setup_bridge(struct pci_bus *bus)
>  	}
>  	pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, l);
>  
> -	/* Clear out the upper 32 bits of PREF base. */
> -	pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, 0);
> +	/* Set up the upper 32 bits of PREF base/limit. */
> +	l = region.start >> 16 >> 16;

We have the little upper_32_bits() helper for this.

> +	pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, l);
> +	l = region.end >> 16 >> 16;
> +	pci_write_config_dword(bridge, PCI_PREF_LIMIT_UPPER32, l);
>  
>  	pci_write_config_word(bridge, PCI_BRIDGE_CONTROL, bus->bridge_ctl);
>  }