PCI: improve resource allocation under transparent bridges

We could run out of space under under 4g, but devices under transparent
bridges can use 64bit resources, so keep trying on the parent bus until
we hit a non-transparent bridge.

Impact: better support for assigning unassigned resources

Reviewed-by: Ivan Kokshaysky <[e-mail]>
Signed-off-by: Yinghai Lu <[e-mail]>
Signed-off-by: Jesse Barnes <[e-mail]>

drivers/pci/setup-bus.c

···
 		res = list->res;
 		idx = res - &list->dev->resource[0];
 		if (pci_assign_resource(list->dev, idx)) {
-			/* FIXME: get rid of this */
 			res->start = 0;
 			res->end = 0;
 			res->flags = 0;

drivers/pci/setup-res.c

···
 }
 #endif	/* CONFIG_PCI_QUIRKS */
 
-int pci_assign_resource(struct pci_dev *dev, int resno)
+static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
+				 int resno)
 {
-	struct pci_bus *bus = dev->bus;
 	struct resource *res = dev->resource + resno;
 	resource_size_t size, min, align;
 	int ret;
 
 	size = resource_size(res);
 	min = (res->flags & IORESOURCE_IO) ? PCIBIOS_MIN_IO : PCIBIOS_MIN_MEM;
-
 	align = resource_alignment(res);
-	if (!align) {
-		dev_info(&dev->dev, "BAR %d: can't allocate resource (bogus "
-			"alignment) %pR flags %#lx\n",
-			resno, res, res->flags);
-		return -EINVAL;
-	}
 
 	/* First, try exact prefetching match.. */
 	ret = pci_bus_alloc_resource(bus, res, size, align, min,
···
 					     pcibios_align_resource, dev);
 	}
 
-	if (ret) {
-		dev_info(&dev->dev, "BAR %d: can't allocate %s resource %pR\n",
-			resno, res->flags & IORESOURCE_IO ? "I/O" : "mem", res);
-	} else {
+	if (!ret) {
 		res->flags &= ~IORESOURCE_STARTALIGN;
 		if (resno < PCI_BRIDGE_RESOURCES)
 			pci_update_resource(dev, resno);
 	}
+
+	return ret;
+}
+
+int pci_assign_resource(struct pci_dev *dev, int resno)
+{
+	struct resource *res = dev->resource + resno;
+	resource_size_t align;
+	struct pci_bus *bus;
+	int ret;
+
+	align = resource_alignment(res);
+	if (!align) {
+		dev_info(&dev->dev, "BAR %d: can't allocate resource (bogus "
+			"alignment) %pR flags %#lx\n",
+			resno, res, res->flags);
+		return -EINVAL;
+	}
+
+	bus = dev->bus;
+	while ((ret = __pci_assign_resource(bus, dev, resno))) {
+		if (bus->parent && bus->self->transparent)
+			bus = bus->parent;
+		else
+			bus = NULL;
+		if (bus)
+			continue;
+		break;
+	}
+
+	if (ret)
+		dev_info(&dev->dev, "BAR %d: can't allocate %s resource %pR\n",
+			resno, res->flags & IORESOURCE_IO ? "I/O" : "mem", res);
 
 	return ret;
 }