[PATCH v8 04/24] PCI: Add version of release_child_resources() aware of fixed BARs

[Sergei Miroshnichenko <s.miroshnichenko@yadro.com>]

When release_child_resources() is applied to a bridge window, it drops the
.start field of children BARs to zero, but the STARTALIGN flag remains set,
leaving the resource in a state not valid for later re-assignment.

Fixed BARs must preserve their offset and size: those marked with the
PCI_FIXED or which are bound by drivers without support of the movable BARs
feature.

Add the pci_release_child_resources() to replace release_child_resources()
in handling the described PCI-specific cases.

Signed-off-by: Sergei Miroshnichenko <s.miroshnichenko@yadro.com>
---
 drivers/pci/setup-bus.c | 53 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index bbcef1a053ab..1370e798db30 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1510,6 +1510,56 @@ static void __pci_bridge_assign_resources(const struct pci_dev *bridge,
 	(IORESOURCE_IO | IORESOURCE_MEM | IORESOURCE_PREFETCH |\
 	 IORESOURCE_MEM_64)
 
+/*
+ * Similar to generic release_child_resources(), but aware of fixed BARs and the
+ * STARTALIGN flag.
+ */
+static void pci_release_child_resources(struct pci_bus *bus, struct resource *r)
+{
+	struct pci_dev *dev;
+
+	if (!pci_can_move_bars)
+		return release_child_resources(r);
+
+	if (!bus || !r)
+		return;
+
+	r->child = NULL;
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		int i;
+
+		for (i = 0; i < PCI_NUM_RESOURCES; i++) {
+			struct resource *tmp = &dev->resource[i];
+			resource_size_t size = resource_size(tmp);
+
+			if (!tmp->flags || !tmp->parent)
+				continue;
+
+			tmp->parent = NULL;
+			tmp->sibling = NULL;
+
+			pci_release_child_resources(dev->subordinate, tmp);
+
+			tmp->flags &= ~IORESOURCE_STARTALIGN;
+			tmp->flags |= IORESOURCE_SIZEALIGN;
+
+			if (pci_dev_bar_fixed(dev, tmp)) {
+				pci_dbg(dev, "release fixed BAR %d %pR (%s), keep its flags, base and size\n",
+					i, tmp, tmp->name);
+				continue;
+			}
+
+			pci_dbg(dev, "release BAR %d %pR (%s)\n", i, tmp, tmp->name);
+
+			if (i >= PCI_BRIDGE_RESOURCES)
+				tmp->flags = 0;
+			tmp->start = 0;
+			tmp->end = size - 1;
+		}
+	}
+}
+
 static void pci_bridge_release_resources(struct pci_bus *bus,
 					 unsigned long type)
 {
@@ -1550,7 +1600,8 @@ static void pci_bridge_release_resources(struct pci_bus *bus,
 		return;
 
 	/* If there are children, release them all */
-	release_child_resources(r);
+	pci_release_child_resources(bus, r);
+
 	if (!release_resource(r)) {
 		type = old_flags = r->flags & PCI_RES_TYPE_MASK;
 		pci_info(dev, "resource %d %pR released\n",
-- 
2.24.1