Revert "PCI: Distribute available resources for root buses, too"

This reverts commit e96e27f.

Jonathan reported that this commit broke this topology, where all the space
available on bus 02 was assigned to the 02:00.0 bridge window, leaving none
for the e1000 device at 02:00.1:

  pci 0000:00:04.0: bridge window [mem 0x10200000-0x103fffff] to [bus 02-04]
  pci 0000:02:00.0: bridge window [mem 0x10200000-0x103fffff] to [bus 03-04]
  pci 0000:02:00.1: BAR 0: failed to assign [mem size 0x00020000]
  e1000 0000:02:00.1: can't ioremap BAR 0: [??? 0x00000000 flags 0x0]

Link: https://lore.kernel.org/r/20221014124553.0000696f@huawei.com
Reported-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Author: bjorn-helgaas

drivers/pci/setup-bus.c

@@ -1768,10 +1768,7 @@ static void adjust_bridge_window(struct pci_dev *bridge, struct resource *res,
 	}
 
 	res->end = res->start + new_size - 1;
-
-	/* If the resource is part of the add_list remove it now */
-	if (add_list)
-		remove_from_list(add_list, res);
+	remove_from_list(add_list, res);
 }
 
 static void pci_bus_distribute_available_resources(struct pci_bus *bus,
@@ -1926,8 +1923,6 @@ static void pci_bridge_distribute_available_resources(struct pci_dev *bridge,
 	if (!bridge->is_hotplug_bridge)
 		return;
 
-	pci_dbg(bridge, "distributing available resources\n");
-
 	/* Take the initial extra resources from the hotplug port */
 	available_io = bridge->resource[PCI_BRIDGE_IO_WINDOW];
 	available_mmio = bridge->resource[PCI_BRIDGE_MEM_WINDOW];
@@ -1939,59 +1934,6 @@ static void pci_bridge_distribute_available_resources(struct pci_dev *bridge,
 					       available_mmio_pref);
 }
 
-static bool pci_bridge_resources_not_assigned(struct pci_dev *dev)
-{
-	const struct resource *r;
-
-	/*
-	 * Check the child device's resources and if they are not yet
-	 * assigned it means we are configuring them (not the boot
-	 * firmware) so we should be able to extend the upstream
-	 * bridge's (that's the hotplug downstream PCIe port) resources
-	 * in the same way we do with the normal hotplug case.
-	 */
-	r = &dev->resource[PCI_BRIDGE_IO_WINDOW];
-	if (!r->flags || !(r->flags & IORESOURCE_STARTALIGN))
-		return false;
-	r = &dev->resource[PCI_BRIDGE_MEM_WINDOW];
-	if (!r->flags || !(r->flags & IORESOURCE_STARTALIGN))
-		return false;
-	r = &dev->resource[PCI_BRIDGE_PREF_MEM_WINDOW];
-	if (!r->flags || !(r->flags & IORESOURCE_STARTALIGN))
-		return false;
-
-	return true;
-}
-
-static void pci_root_bus_distribute_available_resources(struct pci_bus *bus,
-							struct list_head *add_list)
-{
-	struct pci_dev *dev, *bridge = bus->self;
-
-	for_each_pci_bridge(dev, bus) {
-		struct pci_bus *b;
-
-		b = dev->subordinate;
-		if (!b)
-			continue;
-
-		/*
-		 * Need to check "bridge" here too because it is NULL
-		 * in case of root bus.
-		 */
-		if (bridge && pci_bridge_resources_not_assigned(dev)) {
-			pci_bridge_distribute_available_resources(bridge, add_list);
-			/*
-			 * There is only PCIe upstream port on the bus
-			 * so we don't need to go futher.
-			 */
-			return;
-		}
-
-		pci_root_bus_distribute_available_resources(b, add_list);
-	}
-}
-
 /*
  * First try will not touch PCI bridge res.
  * Second and later try will clear small leaf bridge res.
@@ -2031,8 +1973,6 @@ void pci_assign_unassigned_root_bus_resources(struct pci_bus *bus)
 	 */
 	__pci_bus_size_bridges(bus, add_list);
 
-	pci_root_bus_distribute_available_resources(bus, add_list);
-
 	/* Depth last, allocate resources and update the hardware. */
 	__pci_bus_assign_resources(bus, add_list, &fail_head);
 	if (add_list)