>  
>  static int pirq_via_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
>  {
> -	write_config_nybble(router, 0x55, pirq, irq);
> +	write_config_nybble(router, 0x55, pirq == 4 ? 5 : pirq, irq);
>  	return 1;
>  }


you missed the 
> +        return (x >> 4);
in the original patch... so your code is NOT identical.