[PATCH -v5 0/24] PCI: allocate pci bus num range for unassigned bridge busn + pci rescan cleanup

@@ -136,6 +136,7 @@ struct resource {
 /* PC/ISA/whatever - the normal PC address spaces: IO and memory */
 extern struct resource ioport_resource;
 extern struct resource iomem_resource;
+extern struct resource iobusn_resource;
 
 extern struct resource *request_resource_conflict(struct resource *root, struct resource *new);
 extern int request_resource(struct resource *root, struct resource *new);

@@ -419,6 +419,7 @@ struct pci_bus {
 	struct list_head slots;		/* list of slots on this bus */
 	struct resource *resource[PCI_BRIDGE_RESOURCE_NUM];
 	struct list_head resources;	/* address space routed to this bus */
+	struct resource busn_res;	/* track registered bus num range */
 
 	struct pci_ops	*ops;		/* configuration access functions */
 	void		*sysdata;	/* hook for sys-specific extension */

@@ -38,6 +38,14 @@ struct resource iomem_resource = {
 };
 EXPORT_SYMBOL(iomem_resource);
 
+struct resource iobusn_resource = {
+	.name	= "PCI busn",
+	.start	= 0,
+	.end	= 0xffffff,
+	.flags	= IORESOURCE_BUS,
+};
+EXPORT_SYMBOL(iobusn_resource);
+
 /* constraints to be met while allocating resources */
 struct resource_constraint {
 	resource_size_t min, max, align;

@@ -138,6 +138,23 @@ extern struct resource ioport_resource;
 extern struct resource iomem_resource;
 extern struct resource iobusn_resource;
 
+static inline int busn_domain_nr(resource_size_t busn)
+{
+	return busn >> 8;
+}
+static inline int busn_bus_nr(resource_size_t busn)
+{
+	return busn & 0xff;
+}
+static inline resource_size_t busn_update_bus_nr(resource_size_t busn, int b_nr)
+{
+	return (busn & ~0xff) | (b_nr & 0xff);
+}
+static inline resource_size_t busn(int d_nr, int b_nr)
+{
+	return  ((d_nr & 0xffff) << 8) | (b_nr & 0xff);
+}
+
 extern struct resource *request_resource_conflict(struct resource *root, struct resource *new);
 extern int request_resource(struct resource *root, struct resource *new);
 extern int release_resource(struct resource *new);

@@ -1622,6 +1622,48 @@ err_out:
 	return NULL;
 }
 
+void pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
+{
+	struct resource *res = &b->busn_res;
+	struct resource *parent_res = &iobusn_resource;
+	int ret;
+
+	res->start = busn(pci_domain_nr(b), bus);
+	res->end = busn(pci_domain_nr(b), bus_max);
+	res->flags = IORESOURCE_BUS;
+
+	if (!pci_is_root_bus(b))
+		parent_res = &b->parent->busn_res;
+
+	ret = insert_resource(parent_res, res);
+
+	dev_printk(KERN_DEBUG, &b->dev,
+			"busn_res: %pR %s inserted under %pR\n",
+			res, ret ? "can not be" : "is", parent_res);
+}
+
+void pci_bus_update_busn_res_end(struct pci_bus *b, int bus_max)
+{
+	struct resource *res = &b->busn_res;
+	struct resource old_res = *res;
+
+	res->end = busn_update_bus_nr(res->end, bus_max);
+	dev_printk(KERN_DEBUG, &b->dev,
+			"busn_res: %pR end updated to %pR\n",
+			&old_res, res);
+}
+
+void pci_bus_release_busn_res(struct pci_bus *b)
+{
+	struct resource *res = &b->busn_res;
+	int ret;
+
+	ret = release_resource(res);
+	dev_printk(KERN_DEBUG, &b->dev,
+			"busn_res: %pR %s released\n",
+			res, ret ? "can not be" : "is");
+}
+
 struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
 		struct pci_ops *ops, void *sysdata, struct list_head *resources)
 {

@@ -665,6 +665,9 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops, void *sysdata);
 struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 				    struct pci_ops *ops, void *sysdata,
 				    struct list_head *resources);
+void pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
+void pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
+void pci_bus_release_busn_res(struct pci_bus *b);
 struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
 					     struct pci_ops *ops, void *sysdata,
 					     struct list_head *resources);

@@ -1594,6 +1594,8 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 
 	b->number = b->secondary = bus;
 
+	sprintf(b->name, "PCI Bus %04x:%02x", pci_domain_nr(b), b->number);
+
 	/* Add initial resources to the bus */
 	list_for_each_entry_safe(bus_res, n, resources, list)
 		list_move_tail(&bus_res->list, &b->resources);

@@ -1631,6 +1633,7 @@ void pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
 	res->start = busn(pci_domain_nr(b), bus);
 	res->end = busn(pci_domain_nr(b), bus_max);
 	res->flags = IORESOURCE_BUS;
+	res->name = b->name;
 
 	if (!pci_is_root_bus(b))
 		parent_res = &b->parent->busn_res;

@@ -113,6 +113,30 @@ static const struct seq_operations resource_op = {
 	.show	= r_show,
 };
 
+static int busn_r_show(struct seq_file *m, void *v)
+{
+	struct resource *root = m->private;
+	struct resource *r = v, *p;
+	int depth;
+
+	for (depth = 0, p = r; depth < MAX_IORES_LEVEL; depth++, p = p->parent)
+		if (p->parent == root)
+			break;
+	seq_printf(m, "%*s%04x:%02x-%04x:%02x : %s\n",
+			depth * 2, "",
+			busn_domain_nr(r->start), busn_bus_nr(r->start),
+			busn_domain_nr(r->end), busn_bus_nr(r->end),
+			r->name ? r->name : "<BAD>");
+	return 0;
+}
+
+static const struct seq_operations busn_resource_op = {
+	.start	= r_start,
+	.next	= r_next,
+	.stop	= r_stop,
+	.show	= busn_r_show,
+};
+
 static int ioports_open(struct inode *inode, struct file *file)
 {
 	int res = seq_open(file, &resource_op);

@@ -133,6 +157,16 @@ static int iomem_open(struct inode *inode, struct file *file)
 	return res;
 }
 
+static int iobusn_open(struct inode *inode, struct file *file)
+{
+	int res = seq_open(file, &busn_resource_op);
+	if (!res) {
+		struct seq_file *m = file->private_data;
+		m->private = &iobusn_resource;
+	}
+	return res;
+}
+
 static const struct file_operations proc_ioports_operations = {
 	.open		= ioports_open,
 	.read		= seq_read,

@@ -147,10 +181,18 @@ static const struct file_operations proc_iomem_operations = {
 	.release	= seq_release,
 };
 
+static const struct file_operations proc_iobusn_operations = {
+	.open		= iobusn_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
 static int __init ioresources_init(void)
 {
 	proc_create("ioports", 0, NULL, &proc_ioports_operations);
 	proc_create("iomem", 0, NULL, &proc_iomem_operations);
+	proc_create("iobusn", 0, NULL, &proc_iobusn_operations);
 	return 0;
 }
 __initcall(ioresources_init);

@@ -1667,8 +1667,9 @@ void pci_bus_release_busn_res(struct pci_bus *b)
 			res, ret ? "can not be" : "is");
 }
 
-struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
-		struct pci_ops *ops, void *sysdata, struct list_head *resources)
+struct pci_bus * __devinit pci_scan_root_bus_max(struct device *parent, int bus,
+		int bus_max, struct pci_ops *ops, void *sysdata,
+		struct list_head *resources)
 {
 	struct pci_bus *b;
 

@@ -1676,10 +1677,26 @@ struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
 	if (!b)
 		return NULL;
 
+	pci_bus_insert_busn_res(b, bus, bus_max);
 	b->subordinate = pci_scan_child_bus(b);
 	pci_bus_add_devices(b);
 	return b;
 }
+EXPORT_SYMBOL(pci_scan_root_bus_max);
+
+struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
+		struct pci_ops *ops, void *sysdata,
+		struct list_head *resources)
+{
+	struct pci_bus *b;
+
+	b = pci_scan_root_bus_max(parent, bus, 255, ops, sysdata, resources);
+
+	if (b)
+		pci_bus_update_busn_res_end(b, b->subordinate);
+
+	return b;
+}
 EXPORT_SYMBOL(pci_scan_root_bus);
 
 /* Deprecated; use pci_scan_root_bus() instead */

@@ -1692,9 +1709,11 @@ struct pci_bus * __devinit pci_scan_bus_parented(struct device *parent,
 	pci_add_resource(&resources, &ioport_resource);
 	pci_add_resource(&resources, &iomem_resource);
 	b = pci_create_root_bus(parent, bus, ops, sysdata, &resources);
-	if (b)
+	if (b) {
+		pci_bus_insert_busn_res(b, bus, 255);
 		b->subordinate = pci_scan_child_bus(b);
-	else
+		pci_bus_update_busn_res_end(b, b->subordinate);
+	} else
 		pci_free_resource_list(&resources);
 	return b;
 }

@@ -1710,7 +1729,10 @@ struct pci_bus * __devinit pci_scan_bus(int bus, struct pci_ops *ops,
 	pci_add_resource(&resources, &iomem_resource);
 	b = pci_create_root_bus(NULL, bus, ops, sysdata, &resources);
 	if (b) {
+		pci_bus_insert_busn_res(b, bus, 255);
 		b->subordinate = pci_scan_child_bus(b);
+		pci_bus_update_busn_res_end(b, b->subordinate);
+
 		pci_bus_add_devices(b);
 	} else {
 		pci_free_resource_list(&resources);

@@ -68,6 +68,7 @@ void pci_remove_bus(struct pci_bus *pci_bus)
 
 	down_write(&pci_bus_sem);
 	list_del(&pci_bus->node);
+	pci_bus_release_busn_res(pci_bus);
 	up_write(&pci_bus_sem);
 	if (!pci_bus->is_added)
 		return;

@@ -668,6 +668,10 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 void pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
 void pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
 void pci_bus_release_busn_res(struct pci_bus *b);
+struct pci_bus * __devinit pci_scan_root_bus_max(struct device *parent, int bus,
+					     int busmax, struct pci_ops *ops,
+					     void *sysdata,
+					     struct list_head *resources);
 struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
 					     struct pci_ops *ops, void *sysdata,
 					     struct list_head *resources);

@@ -172,7 +172,8 @@ static inline void arch_fix_phys_package_id(int num, u32 slot)
 }
 
 struct pci_bus;
-void x86_pci_root_bus_resources(int bus, struct list_head *resources);
+void x86_pci_root_bus_resources(int bus, int *bus_max,
+				struct list_head *resources);
 
 #ifdef CONFIG_SMP
 #define mc_capable()	((boot_cpu_data.x86_max_cores > 1) && \

@@ -348,6 +348,7 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
 	struct acpi_device *device = root->device;
 	int domain = root->segment;
 	int busnum = root->secondary.start;
+	int busmax = root->secondary.end;
 	LIST_HEAD(resources);
 	struct pci_bus *bus;
 	struct pci_sysdata *sd;

@@ -410,12 +411,13 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
 		 * defaults or native bridge info if we're ignoring _CRS.
 		 */
 		if (!pci_use_crs)
-			x86_pci_root_bus_resources(busnum, &resources);
+			x86_pci_root_bus_resources(busnum, &busmax, &resources);
 		bus = pci_create_root_bus(NULL, busnum, &pci_root_ops, sd,
 					  &resources);
-		if (bus)
+		if (bus) {
+			pci_bus_insert_busn_res(bus, busnum, busmax);
 			bus->subordinate = pci_scan_child_bus(bus);
-		else
+		} else
 			pci_free_resource_list(&resources);
 	}
 

@@ -7,7 +7,8 @@
 int pci_root_num;
 struct pci_root_info pci_root_info[PCI_ROOT_NR];
 
-void x86_pci_root_bus_resources(int bus, struct list_head *resources)
+void x86_pci_root_bus_resources(int bus, int *bus_max,
+				struct list_head *resources)
 {
 	int i;
 	int j;

@@ -28,6 +29,7 @@ void x86_pci_root_bus_resources(int bus, struct list_head *resources)
 	       bus);
 
 	info = &pci_root_info[i];
+	*bus_max = info->bus_max;
 	for (j = 0; j < info->res_num; j++) {
 		struct resource *res;
 		struct resource *root;

@@ -51,6 +53,10 @@ default_resources:
 	printk(KERN_DEBUG "PCI: root bus %02x: using default resources\n", bus);
 	pci_add_resource(resources, &ioport_resource);
 	pci_add_resource(resources, &iomem_resource);
+	if (!bus)
+		*bus_max = 0xff;
+	else if (!*bus_max)
+		*bus_max = bus;
 }
 
 void __devinit update_res(struct pci_root_info *info, resource_size_t start,

@@ -433,6 +433,7 @@ struct pci_bus * __devinit pcibios_scan_root(int busnum)
 	LIST_HEAD(resources);
 	struct pci_bus *bus = NULL;
 	struct pci_sysdata *sd;
+	int bus_max;
 
 	while ((bus = pci_find_next_bus(bus)) != NULL) {
 		if (bus->number == busnum) {

@@ -454,8 +455,9 @@ struct pci_bus * __devinit pcibios_scan_root(int busnum)
 	sd->node = get_mp_bus_to_node(busnum);
 
 	printk(KERN_DEBUG "PCI: Probing PCI hardware (bus %02x)\n", busnum);
-	x86_pci_root_bus_resources(busnum, &resources);
-	bus = pci_scan_root_bus(NULL, busnum, &pci_root_ops, sd, &resources);
+	x86_pci_root_bus_resources(busnum, &bus_max, &resources);
+	bus = pci_scan_root_bus_max(NULL, busnum, bus_max, &pci_root_ops, sd,
+				&resources);
 	if (!bus) {
 		pci_free_resource_list(&resources);
 		kfree(sd);

@@ -643,6 +645,7 @@ struct pci_bus * __devinit pci_scan_bus_on_node(int busno, struct pci_ops *ops,
 	LIST_HEAD(resources);
 	struct pci_bus *bus = NULL;
 	struct pci_sysdata *sd;
+	int bus_max;
 
 	/*
 	 * Allocate per-root-bus (not per bus) arch-specific data.

@@ -655,8 +658,8 @@ struct pci_bus * __devinit pci_scan_bus_on_node(int busno, struct pci_ops *ops,
 		return NULL;
 	}
 	sd->node = node;
-	x86_pci_root_bus_resources(busno, &resources);
-	bus = pci_scan_root_bus(NULL, busno, ops, sd, &resources);
+	x86_pci_root_bus_resources(busno, &bus_max, &resources);
+	bus = pci_scan_root_bus_max(NULL, busno, bus_max, ops, sd, &resources);
 	if (!bus) {
 		pci_free_resource_list(&resources);
 		kfree(sd);

@@ -331,6 +331,7 @@ pci_acpi_scan_root(struct acpi_pci_root *root)
 	struct acpi_device *device = root->device;
 	int domain = root->segment;
 	int bus = root->secondary.start;
+	int busmax = root->secondary.end;
 	struct pci_controller *controller;
 	unsigned int windows = 0;
 	struct pci_root_info info;

@@ -384,6 +385,7 @@ pci_acpi_scan_root(struct acpi_pci_root *root)
 		return NULL;
 	}
 
+	pci_bus_insert_busn_res(pbus, busnum, busmax);
 	pbus->subordinate = pci_scan_child_bus(pbus);
 	return pbus;
 

@@ -1732,6 +1732,8 @@ void __devinit pcibios_scan_phb(struct pci_controller *hose)
 	bus->secondary = hose->first_busno;
 	hose->bus = bus;
 
+	pci_bus_insert_busn_res(bus, hose->first_busno, hose->last_busno);
+
 	/* Get probe mode and perform scan */
 	mode = PCI_PROBE_NORMAL;
 	if (node && ppc_md.pci_probe_mode)

@@ -1742,8 +1744,11 @@ void __devinit pcibios_scan_phb(struct pci_controller *hose)
 		of_scan_bus(node, bus);
 	}
 
-	if (mode == PCI_PROBE_NORMAL)
+	if (mode == PCI_PROBE_NORMAL) {
+		pci_bus_update_busn_res_end(bus, 255);
 		hose->last_busno = bus->subordinate = pci_scan_child_bus(bus);
+		pci_bus_update_busn_res_end(bus, bus->subordinate);
+	}
 
 	/* Platform gets a chance to do some global fixups before
 	 * we proceed to resource allocation

@@ -624,6 +624,42 @@ static void pci_fixup_parent_subordinate_busnr(struct pci_bus *child, int max)
 	}
 }
 
+static void __devinit pci_bus_update_top(struct pci_bus *parent,
+		 long size, struct resource *parent_res)
+{
+	struct resource *res;
+
+	if (!size)
+		return;
+
+	while (parent) {
+		res = &parent->busn_res;
+		if (res == parent_res)
+			break;
+		res->end += size;
+		parent->subordinate += size;
+		pci_write_config_byte(parent->self, PCI_SUBORDINATE_BUS,
+					 parent->subordinate);
+		dev_printk(KERN_DEBUG, &parent->dev,
+				"busn_res: %s %02lx to %pR\n",
+				(size > 0) ? "extended" : "shrunk",
+				abs(size), res);
+		parent = parent->parent;
+	}
+}
+
+static void __devinit pci_bus_extend_top(struct pci_bus *parent,
+		 long size, struct resource *parent_res)
+{
+	pci_bus_update_top(parent, size, parent_res);
+}
+
+static void __devinit pci_bus_shrink_top(struct pci_bus *parent,
+		 long size, struct resource *parent_res)
+{
+	pci_bus_update_top(parent, -size, parent_res);
+}
+
 /*
  * If it's a bridge, configure it and scan the bus behind it.
  * For CardBus bridges, we don't scan behind as the devices will

@@ -1014,7 +1014,9 @@ static int __init dino_probe(struct parisc_device *dev)
 		return 0;
 	}
 
+	pci_bus_insert_busn_res(bus, dino_current_bus, 255);
 	bus->subordinate = pci_scan_child_bus(bus);
+	pci_bus_update_busn_res_end(bus, bus->subordinate);
 
 	/* This code *depends* on scanning being single threaded
 	 * if it isn't, this global bus number count will fail

@@ -1531,6 +1531,9 @@ lba_driver_probe(struct parisc_device *dev)
 		return 0;
 	}
 
+	pci_bus_insert_busn_res(lba_bus, lba_dev->hba.bus_num.start,
+				lba_dev->hba.bus_num.end);
+
 	lba_bus->subordinate = pci_scan_child_bus(lba_bus);
 
 	/* This is in lieu of calling pci_assign_unassigned_resources() */

@@ -770,6 +770,31 @@ reduce_needed_size:
 	return ret;
 }
 
+static int __devinit pci_bridge_check_busn_broken(struct pci_bus *bus,
+				struct pci_dev *dev,
+				int secondary, int subordinate)
+{
+	int broken = 0;
+
+	struct resource busn_res;
+	int ret;
+
+	memset(&busn_res, 0, sizeof(struct resource));
+	dev_printk(KERN_DEBUG, &dev->dev,
+		 "check if busn %02x-%02x is in busn_res: %pR\n",
+		 secondary, subordinate, &bus->busn_res);
+	ret = allocate_resource(&bus->busn_res, &busn_res,
+			 (subordinate - secondary + 1),
+			 busn(pci_domain_nr(bus), secondary),
+			 busn(pci_domain_nr(bus), subordinate),
+			 1, NULL, NULL);
+	if (ret)
+		broken = 1;
+	else
+		release_resource(&busn_res);
+
+	return broken;
+}
 /*
  * If it's a bridge, configure it and scan the bus behind it.
  * For CardBus bridges, we don't scan behind as the devices will

@@ -809,10 +809,11 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 {
 	struct pci_bus *child;
 	int is_cardbus = (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS);
-	u32 buses, i, j = 0;
+	u32 buses;
 	u16 bctl;
 	u8 primary, secondary, subordinate;
 	int broken = 0;
+	struct resource *parent_res = NULL;
 
 	pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses);
 	primary = buses & 0xFF;

@@ -824,10 +825,16 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 
 	/* Check if setup is sensible at all */
 	if (!pass &&
-	    (primary != bus->number || secondary <= bus->number)) {
-		dev_dbg(&dev->dev, "bus configuration invalid, reconfiguring\n");
+	    (primary != bus->number || secondary <= bus->number))
 		broken = 1;
-	}
+
+	/* more strict checking */
+	if (!pass && !broken && !dev->subordinate)
+		broken = pci_bridge_check_busn_broken(bus, dev,
+						   secondary, subordinate);
+
+	if (broken)
+		dev_dbg(&dev->dev, "bus configuration invalid, reconfiguring\n");
 
 	/* Disable MasterAbortMode during probing to avoid reporting
 	   of bus errors (in some architectures) */ 

@@ -860,6 +867,8 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 			child->primary = primary;
 			child->subordinate = subordinate;
 			child->bridge_ctl = bctl;
+
+			pci_bus_insert_busn_res(child, secondary, subordinate);
 		}
 
 		cmax = pci_scan_child_bus(child);

@@ -872,6 +881,11 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 		 * We need to assign a number to this bus which we always
 		 * do in the second pass.
 		 */
+		long shrink_size;
+		struct resource busn_res;
+		int ret = -ENOMEM;
+		int old_max = max;
+
 		if (!pass) {
 			if (pcibios_assign_all_busses() || broken)
 				/* Temporarily disable forwarding of the

@@ -888,20 +902,44 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 		/* Clear errors */
 		pci_write_config_word(dev, PCI_STATUS, 0xffff);
 
-		/* Prevent assigning a bus number that already exists.
-		 * This can happen when a bridge is hot-plugged, so in
-		 * this case we only re-scan this bus. */
-		child = pci_find_bus(pci_domain_nr(bus), max+1);
-		if (!child) {
-			child = pci_add_new_bus(bus, dev, ++max);
-			if (!child)
-				goto out;
+		if (dev->subordinate) {
+			/* We get here only for cardbus */
+			child = dev->subordinate;
+			if  (!is_cardbus)
+				dev_warn(&dev->dev,
+				 "rescan scaned bridge as broken one again ?");
+
+			goto out;
 		}
+		/*
+		 * For CardBus bridges, we leave 4 bus numbers
+		 * as cards with a PCI-to-PCI bridge can be
+		 * inserted later.
+		 * other just allocate 8 bus to avoid we fall into
+		 *  small hole in the middle.
+		 */
+		ret = pci_bridge_probe_busn_res(bus, dev, &busn_res,
+				is_cardbus ? (CARDBUS_RESERVE_BUSNR + 1) : 8,
+				&parent_res);
+
+		if (ret != 0)
+			goto out;
+
+		child = pci_add_new_bus(bus, dev, busn_bus_nr(busn_res.start));
+		if (!child)
+			goto out;
+
+		child->subordinate = busn_bus_nr(busn_res.end);
+		pci_bus_insert_busn_res(child, busn_bus_nr(busn_res.start),
+					busn_bus_nr(busn_res.end));
+
 		buses = (buses & 0xff000000)
 		      | ((unsigned int)(child->primary)     <<  0)
 		      | ((unsigned int)(child->secondary)   <<  8)
 		      | ((unsigned int)(child->subordinate) << 16);
 
+		max = child->subordinate;
+
 		/*
 		 * yenta.c forces a secondary latency timer of 176.
 		 * Copy that behaviour here.

@@ -932,43 +970,24 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 			 * the real value of max.
 			 */
 			pci_fixup_parent_subordinate_busnr(child, max);
+
 		} else {
-			/*
-			 * For CardBus bridges, we leave 4 bus numbers
-			 * as cards with a PCI-to-PCI bridge can be
-			 * inserted later.
-			 */
-			for (i=0; i<CARDBUS_RESERVE_BUSNR; i++) {
-				struct pci_bus *parent = bus;
-				if (pci_find_bus(pci_domain_nr(bus),
-							max+i+1))
-					break;
-				while (parent->parent) {
-					if ((!pcibios_assign_all_busses()) &&
-					    (parent->subordinate > max) &&
-					    (parent->subordinate <= max+i)) {
-						j = 1;
-					}
-					parent = parent->parent;
-				}
-				if (j) {
-					/*
-					 * Often, there are two cardbus bridges
-					 * -- try to leave one valid bus number
-					 * for each one.
-					 */
-					i /= 2;
-					break;
-				}
-			}
-			max += i;
 			pci_fixup_parent_subordinate_busnr(child, max);
 		}
 		/*
 		 * Set the subordinate bus number to its real value.
 		 */
+		shrink_size = child->subordinate - max;
 		child->subordinate = max;
 		pci_write_config_byte(dev, PCI_SUBORDINATE_BUS, max);
+		pci_bus_update_busn_res_end(child, max);
+
+		/* shrink some back, if we extend top before */
+		if (!is_cardbus && (shrink_size > 0) && parent_res)
+			pci_bus_shrink_top(bus, shrink_size, parent_res);
+
+		if (old_max > max)
+			max = old_max;
 	}
 
 	sprintf(child->name,

@@ -608,22 +608,6 @@ struct pci_bus *__ref pci_add_new_bus(struct pci_bus *parent, struct pci_dev *de
 	return child;
 }
 
-static void pci_fixup_parent_subordinate_busnr(struct pci_bus *child, int max)
-{
-	struct pci_bus *parent = child->parent;
-
-	/* Attempts to fix that up are really dangerous unless
-	   we're going to re-assign all bus numbers. */
-	if (!pcibios_assign_all_busses())
-		return;
-
-	while (parent->parent && parent->subordinate < max) {
-		parent->subordinate = max;
-		pci_write_config_byte(parent->self, PCI_SUBORDINATE_BUS, max);
-		parent = parent->parent;
-	}
-}
-
 static void __devinit pci_bus_update_top(struct pci_bus *parent,
 		 long size, struct resource *parent_res)
 {

@@ -956,23 +940,7 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 
 		if (!is_cardbus) {
 			child->bridge_ctl = bctl;
-			/*
-			 * Adjust subordinate busnr in parent buses.
-			 * We do this before scanning for children because
-			 * some devices may not be detected if the bios
-			 * was lazy.
-			 */
-			pci_fixup_parent_subordinate_busnr(child, max);
-			/* Now we can scan all subordinate buses... */
 			max = pci_scan_child_bus(child);
-			/*
-			 * now fix it up again since we have found
-			 * the real value of max.
-			 */
-			pci_fixup_parent_subordinate_busnr(child, max);
-
-		} else {
-			pci_fixup_parent_subordinate_busnr(child, max);
 		}
 		/*
 		 * Set the subordinate bus number to its real value.

@@ -779,6 +779,9 @@ static int __devinit pci_bridge_check_busn_broken(struct pci_bus *bus,
 
 	return broken;
 }
+
+static unsigned int __devinit __pci_scan_child_bus(struct pci_bus *bus,
+						 int pass);
 /*
  * If it's a bridge, configure it and scan the bus behind it.
  * For CardBus bridges, we don't scan behind as the devices will

@@ -830,11 +833,10 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 	    !is_cardbus && !broken) {
 		unsigned int cmax;
 		/*
-		 * Bus already configured by firmware, process it in the first
-		 * pass and just note the configuration.
+		 * Bus already configured by firmware, still process it in two
+		 * passes in extreme case like two adjaced bridges have children
+		 * bridges that are not setup properly.
 		 */
-		if (pass)
-			goto out;
 
 		/*
 		 * If we already got to this bus through a different bridge,

@@ -855,7 +857,7 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 			pci_bus_insert_busn_res(child, secondary, subordinate);
 		}
 
-		cmax = pci_scan_child_bus(child);
+		cmax = __pci_scan_child_bus(child, pass);
 		if (cmax > max)
 			max = cmax;
 		if (child->subordinate > max)

@@ -1651,12 +1653,13 @@ void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss)
 }
 EXPORT_SYMBOL_GPL(pcie_bus_configure_settings);
 
-unsigned int __devinit pci_scan_child_bus(struct pci_bus *bus)
+static unsigned int __devinit __pci_scan_child_bus(struct pci_bus *bus,
+						 int pass)
 {
-	unsigned int devfn, pass, max = bus->secondary;
+	unsigned int devfn, max = bus->secondary;
 	struct pci_dev *dev;
 
-	dev_dbg(&bus->dev, "scanning bus\n");
+	dev_dbg(&bus->dev, "scanning bus pass %d\n", pass);
 
 	/* Go find them, Rover! */
 	for (devfn = 0; devfn < 0x100; devfn += 8)

@@ -1670,18 +1673,16 @@ unsigned int __devinit pci_scan_child_bus(struct pci_bus *bus)
 	 * all PCI-to-PCI bridges on this bus.
 	 */
 	if (!bus->is_added) {
-		dev_dbg(&bus->dev, "fixups for bus\n");
+		dev_dbg(&bus->dev, "fixups for bus pass %d\n", pass);
 		pcibios_fixup_bus(bus);
 		if (pci_is_root_bus(bus))
 			bus->is_added = 1;
 	}
 
-	for (pass=0; pass < 2; pass++)
-		list_for_each_entry(dev, &bus->devices, bus_list) {
-			if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE ||
-			    dev->hdr_type == PCI_HEADER_TYPE_CARDBUS)
-				max = pci_scan_bridge(bus, dev, max, pass);
-		}
+	list_for_each_entry(dev, &bus->devices, bus_list)
+		if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE ||
+		    dev->hdr_type == PCI_HEADER_TYPE_CARDBUS)
+			max = pci_scan_bridge(bus, dev, max, pass);
 
 	/*
 	 * We've scanned the bus and so we know all about what's on

@@ -1690,7 +1691,24 @@ unsigned int __devinit pci_scan_child_bus(struct pci_bus *bus)
 	 *
 	 * Return how far we've got finding sub-buses.
 	 */
-	dev_dbg(&bus->dev, "bus scan returning with max=%02x\n", max);
+	dev_dbg(&bus->dev, "bus scan returning with max=%02x pass %d\n",
+			max, pass);
+
+	return max;
+}
+
+unsigned int __devinit pci_scan_child_bus(struct pci_bus *bus)
+{
+	int pass;
+	unsigned int max = 0, tmp;
+
+	for (pass = 0; pass < 2;  pass++) {
+		tmp = __pci_scan_child_bus(bus, pass);
+
+		if (tmp > max)
+			max = tmp;
+	}
+
 	return max;
 }