AGP_I915_IFPADDR
temp = pci_read_config(sc->bdev, AGP_I915_IFPADDR, 4);
pci_write_config(sc->bdev, AGP_I915_IFPADDR, temp | 1, 4);
temp = pci_read_config(sc->bdev, AGP_I915_IFPADDR, 4);
pci_write_config(sc->bdev, AGP_I915_IFPADDR, temp, 4);