[PATCH 1/2] pci: release that leaf bridge' resource index is not used -v6

[Yinghai Lu <yinghai@kernel.org>]

only for index < 3

v2: Jesse doesn't like it is in find_free_bus_resource...
    try to move out of pci_bus_size_bridges loop.
need to apply after:
	[PATCH] pci: pciehp update the slot bridge res to get big range for pcie devices - v4
v3: add pci_setup_bridge calling after pci_bridge_release_not_used_res.
    only clear release those res for x86.
v4: Bjorn want to release use dev instead of bus.
v5: Kenji pointed out it will have problem with several level bridge.
    so let only handle leaf bridge.
v6: address Kenji's request (new pci_bus_release...). and change applying order
    move back release to pci_assign_unassigned_resource

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 drivers/pci/setup-bus.c |   65 +++++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/pci.h     |    1 
 2 files changed, 65 insertions(+), 1 deletion(-)

Index: linux-2.6/drivers/pci/setup-bus.c
===================================================================
--- linux-2.6.orig/drivers/pci/setup-bus.c
+++ linux-2.6/drivers/pci/setup-bus.c
@@ -573,13 +573,68 @@ void __ref pci_bus_assign_resources(cons
 }
 EXPORT_SYMBOL(pci_bus_assign_resources);
 
+static void pci_bridge_release_not_used_res(struct pci_bus *bus)
+{
+	int idx;
+	bool changed = false;
+	struct pci_dev *dev;
+	struct resource *r;
+	unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
+				  IORESOURCE_PREFETCH;
+
+	/* for pci bridges res only */
+	dev = bus->self;
+	for (idx = PCI_BRIDGE_RESOURCES; idx < PCI_BRIDGE_RESOURCES + 3;
+	    idx++) {
+		r = &dev->resource[idx];
+		if (!(r->flags & type_mask))
+			continue;
+		if (!r->parent)
+			continue;
+		/* if there is no child under that, we should release it */
+		if (r->child)
+			continue;
+		if (!release_resource(r)) {
+			dev_info(&dev->dev, "resource %d %pRt released\n",
+				 idx, r);
+			r->flags = 0;
+			changed = true;
+		}
+	}
+
+	if (changed)
+		pci_setup_bridge(bus);
+}
+
+void __ref pci_bus_release_bridges_not_used_res(struct pci_bus *bus)
+{
+	struct pci_bus *b;
+
+	/* If the bus is cardbus, do nothing */
+	if (bus->self && (bus->self->class >> 8) == PCI_CLASS_BRIDGE_CARDBUS)
+		return;
+
+	/* We only release the resources under the leaf bridge */
+	if (list_empty(&bus->children)) {
+		if (!pci_is_root_bus(bus))
+			pci_bridge_release_not_used_res(bus);
+		return;
+	}
+
+	/* Scan child buses if the bus is not leaf */
+	list_for_each_entry(b, &bus->children, node)
+		pci_bus_release_bridges_not_used_res(b);
+}
+EXPORT_SYMBOL(pci_bus_release_bridges_not_used_res);
+
 static void pci_bus_dump_res(struct pci_bus *bus)
 {
         int i;
 
         for (i = 0; i < PCI_BUS_NUM_RESOURCES; i++) {
                 struct resource *res = bus->resource[i];
-                if (!res || !res->end)
+
+		if (!res || !res->end || !res->flags)
                         continue;
 
 		dev_printk(KERN_DEBUG, &bus->dev, "resource %d %pRt\n", i, res);
@@ -608,6 +663,14 @@ pci_assign_unassigned_resources(void)
 {
 	struct pci_bus *bus;
 
+	/*
+	 * Try to release leaf bridge's resources that there is not child
+	 * under it
+	 */
+	list_for_each_entry(bus, &pci_root_buses, node) {
+		pci_bus_release_bridges_not_used_res(bus);
+	}
+
 	/* Depth first, calculate sizes and alignments of all
 	   subordinate buses. */
 	list_for_each_entry(bus, &pci_root_buses, node) {
Index: linux-2.6/include/linux/pci.h
===================================================================
--- linux-2.6.orig/include/linux/pci.h
+++ linux-2.6/include/linux/pci.h
@@ -758,6 +758,7 @@ int pci_vpd_truncate(struct pci_dev *dev
 /* Helper functions for low-level code (drivers/pci/setup-[bus,res].c) */
 void pci_bus_assign_resources(const struct pci_bus *bus);
 void pci_bus_size_bridges(struct pci_bus *bus);
+void pci_bus_release_bridges_not_used_res(struct pci_bus *bus);
 int pci_claim_resource(struct pci_dev *, int);
 void pci_assign_unassigned_resources(void);
 void pdev_enable_device(struct pci_dev *);