Ignore disabled ROM resources at setup

Writing even a disabled value seems to mess up some matrox graphics
cards.  It may be a card-related issue, but we may also be writing
reserved low bits in the result.

This was a fall-out of switching x86 over to the generic PCI resource
allocation code, and needs more debugging.  In particular, the old x86
code defaulted to not doing any resource allocations at all for ROM
resources.

In the meantime, this has been reported to make X happier by Helge
Hafting <helgehaf@aitel.hist.no>.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/pci/setup-res.c

@@ -53,7 +53,9 @@ pci_update_resource(struct pci_dev *dev, struct resource *res, int resno)
 	if (resno < 6) {
 		reg = PCI_BASE_ADDRESS_0 + 4 * resno;
 	} else if (resno == PCI_ROM_RESOURCE) {
-		new |= res->flags & IORESOURCE_ROM_ENABLE;
+		if (!(res->flags & IORESOURCE_ROM_ENABLE))
+			return;
+		new |= PCI_ROM_ADDRESS_ENABLE;
 		reg = dev->rom_base_reg;
 	} else {
 		/* Hmm, non-standard resource. */