[PATCH RFC v4 19/21] PCI: Prioritize fixed BAR assigning over the movable ones

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

The allocated bridge windows are big enough to house all the children
bridges and BARs, but the fixed resources must be assigned first, so the
movable ones later divide the rest of the window. That's the assignment
order:

 1. Bridge windows with fixed areas;
 2. Fixed BARs;
 3. The rest of BARs and bridge windows.

Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
---
 drivers/pci/setup-bus.c | 69 ++++++++++++++++++++++++++++++++---------
 1 file changed, 55 insertions(+), 14 deletions(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index f4737339d5ec..932a6c020d10 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -272,31 +272,54 @@ static void reassign_resources_sorted(struct list_head *realloc_head,
 	}
 }
 
-/**
- * assign_requested_resources_sorted() - satisfy resource requests
- *
- * @head : head of the list tracking requests for resources
- * @fail_head : head of the list tracking requests that could
- *		not be allocated
- *
- * Satisfy resource requests of each element in the list. Add
- * requests that could not satisfied to the failed_list.
- */
-static void assign_requested_resources_sorted(struct list_head *head,
-				 struct list_head *fail_head)
+enum assign_step {
+	assign_fixed_bridge_windows,
+	assign_fixed_resources,
+	assign_float_resources,
+};
+
+static void _assign_requested_resources_sorted(struct list_head *head,
+					       struct list_head *fail_head,
+					       enum assign_step step)
 {
 	struct resource *res;
 	struct pci_dev_resource *dev_res;
 	int idx;
 
 	list_for_each_entry(dev_res, head, list) {
+		bool is_fixed;
+		bool is_fixed_bridge;
+		bool is_bridge;
+
 		if (pci_dev_is_ignored(dev_res->dev))
 			continue;
 
 		res = dev_res->res;
+		if (!resource_size(res))
+			continue;
+
 		idx = res - &dev_res->dev->resource[0];
-		if (resource_size(res) &&
-		    pci_assign_resource(dev_res->dev, idx)) {
+		is_fixed = res->flags & IORESOURCE_PCI_FIXED;
+		is_bridge = dev_res->dev->subordinate && idx >= PCI_BRIDGE_RESOURCES;
+
+		if (is_bridge) {
+			struct pci_bus *child = dev_res->dev->subordinate;
+			int b_res_idx = pci_get_bridge_resource_idx(res);
+			struct resource *fixed_res = &child->fixed_range_hard[b_res_idx];
+
+			is_fixed_bridge = fixed_res->start < fixed_res->end;
+		} else {
+			is_fixed_bridge = false;
+		}
+
+		if (assign_fixed_bridge_windows == step && !is_fixed_bridge)
+			continue;
+		else if (assign_fixed_resources == step && (!is_fixed || is_bridge))
+			continue;
+		else if (assign_float_resources == step && (is_fixed || is_fixed_bridge))
+			continue;
+
+		if (pci_assign_resource(dev_res->dev, idx)) {
 			if (fail_head) {
 				/*
 				 * if the failed res is for ROM BAR, and it will
@@ -315,6 +338,24 @@ static void assign_requested_resources_sorted(struct list_head *head,
 	}
 }
 
+/**
+ * assign_requested_resources_sorted() - satisfy resource requests
+ *
+ * @head : head of the list tracking requests for resources
+ * @fail_head : head of the list tracking requests that could
+ *		not be allocated
+ *
+ * Satisfy resource requests of each element in the list. Add
+ * requests that could not satisfied to the failed_list.
+ */
+static void assign_requested_resources_sorted(struct list_head *head,
+					      struct list_head *fail_head)
+{
+	_assign_requested_resources_sorted(head, fail_head, assign_fixed_bridge_windows);
+	_assign_requested_resources_sorted(head, fail_head, assign_fixed_resources);
+	_assign_requested_resources_sorted(head, fail_head, assign_float_resources);
+}
+
 static unsigned long pci_fail_res_type_mask(struct list_head *fail_head)
 {
 	struct pci_dev_resource *fail_res;
-- 
2.20.1