[PATCH v6 06/30] PCI: hotplug: movable BARs: Recalculate all bridge windows during rescan

[Sergey Miroshnichenko]

When the movable BARs feature is enabled and a rescan has been requested,
release all the bridge windows and recalculate them from scratch, taking
into account all kinds for BARs: fixed, immovable, movable, new.

This increases the chances to find a memory space to fit BARs for newly
hotplugged devices, especially if no/not enough gaps were reserved by the
BIOS/bootloader/firmware.

The last step of writing the recalculated windows to the bridges is done
by the new pci_setup_bridges() function.

Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko at yadro.com>
---
 drivers/pci/pci.h       |  1 +
 drivers/pci/probe.c     | 22 ++++++++++++++++++++++
 drivers/pci/setup-bus.c | 16 ++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 19bc50597d12..4a3f2b69285b 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -280,6 +280,7 @@ void __pci_bus_assign_resources(const struct pci_bus *bus,
 				struct list_head *realloc_head,
 				struct list_head *fail_head);
 bool pci_bus_clip_resource(struct pci_dev *dev, int idx);
+void pci_bus_release_root_bridge_resources(struct pci_bus *bus);
 
 void pci_reassigndev_resource_alignment(struct pci_dev *dev);
 void pci_disable_bridge_window(struct pci_dev *dev);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 3d8c0f653378..d2dbec51c4df 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -3200,6 +3200,25 @@ static void pci_bus_rescan_done(struct pci_bus *bus)
 		pci_config_pm_runtime_put(bus->self);
 }
 
+static void pci_setup_bridges(struct pci_bus *bus)
+{
+	struct pci_dev *dev;
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		struct pci_bus *child;
+
+		if (!pci_dev_is_added(dev))
+			continue;
+
+		child = dev->subordinate;
+		if (child)
+			pci_setup_bridges(child);
+	}
+
+	if (bus->self)
+		pci_setup_bridge(bus);
+}
+
 /**
  * pci_rescan_bus - Scan a PCI bus for devices
  * @bus: PCI bus to scan
@@ -3221,8 +3240,11 @@ unsigned int pci_rescan_bus(struct pci_bus *bus)
 		pci_bus_rescan_prepare(root);
 
 		max = pci_scan_child_bus(root);
+
+		pci_bus_release_root_bridge_resources(root);
 		pci_assign_unassigned_root_bus_resources(root);
 
+		pci_setup_bridges(root);
 		pci_bus_rescan_done(root);
 	} else {
 		max = pci_scan_child_bus(bus);
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index f2f02e6c9000..075e8185b936 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1635,6 +1635,22 @@ static void pci_bus_release_bridge_resources(struct pci_bus *bus,
 		pci_bridge_release_resources(bus, type);
 }
 
+void pci_bus_release_root_bridge_resources(struct pci_bus *root_bus)
+{
+	int i;
+	struct resource *r;
+
+	pci_bus_release_bridge_resources(root_bus, IORESOURCE_IO, whole_subtree);
+	pci_bus_release_bridge_resources(root_bus, IORESOURCE_MEM, whole_subtree);
+	pci_bus_release_bridge_resources(root_bus,
+					 IORESOURCE_MEM_64 | IORESOURCE_PREFETCH,
+					 whole_subtree);
+
+	pci_bus_for_each_resource(root_bus, r, i) {
+		pci_release_child_resources(root_bus, r);
+	}
+}
+
 static void pci_bus_dump_res(struct pci_bus *bus)
 {
 	struct resource *res;
-- 
2.23.0