diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
index 266a7b2d4184..4f0e3ebfea4b 100644
--- a/arch/arm64/kernel/pci.c
+++ b/arch/arm64/kernel/pci.c
@@ -137,25 +137,18 @@ pci_acpi_setup_ecam_mapping(struct acpi_pci_root *root)
 	struct device *dev = &root->device->dev;
 	struct resource *bus_res = &root->secondary;
 	u16 seg = root->segment;
+	struct pci_ecam_ops *ecam_ops;
 	struct resource cfgres;
 	struct acpi_device *adev;
 	struct pci_config_window *cfg;
-	unsigned int bsz;
+	int ret;
 
-	/* Use address from _CBA if present, otherwise lookup MCFG */
-	if (!root->mcfg_addr)
-		root->mcfg_addr = pci_mcfg_lookup(seg, bus_res);
-
-	if (!root->mcfg_addr) {
+	ret = pci_mcfg_lookup(root, &cfgres, &ecam_ops);
+	if (ret) {
 		dev_err(dev, "%04x:%pR ECAM region not found\n", seg, bus_res);
 		return NULL;
 	}
 
-	bsz = 1 << pci_generic_ecam_ops.bus_shift;
-	cfgres.start = root->mcfg_addr + bus_res->start * bsz;
-	cfgres.end = cfgres.start + resource_size(bus_res) * bsz - 1;
-	cfgres.flags = IORESOURCE_MEM;
-
 	adev = acpi_resource_consumer(&cfgres);
 	if (adev)
 		dev_info(dev, "ECAM area %pR reserved by %s\n", &cfgres,
@@ -164,7 +157,7 @@ pci_acpi_setup_ecam_mapping(struct acpi_pci_root *root)
 		dev_warn(dev, FW_BUG "ECAM area %pR not reserved in ACPI namespace\n",
 			 &cfgres);
 
-	cfg = pci_ecam_create(dev, &cfgres, bus_res, &pci_generic_ecam_ops);
+	cfg = pci_ecam_create(dev, &cfgres, bus_res, ecam_ops);
 	if (IS_ERR(cfg)) {
 		dev_err(dev, "%04x:%pR error %ld mapping ECAM\n", seg, bus_res,
 			PTR_ERR(cfg));
diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
index b5b376e081f5..ffcc6513e851 100644
--- a/drivers/acpi/pci_mcfg.c
+++ b/drivers/acpi/pci_mcfg.c
@@ -22,6 +22,7 @@
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/pci-acpi.h>
+#include <linux/pci-ecam.h>
 
 /* Structure to hold entries from the MCFG table */
 struct mcfg_entry {
@@ -35,9 +36,18 @@ struct mcfg_entry {
 /* List to save MCFG entries */
 static LIST_HEAD(pci_mcfg_list);
 
-phys_addr_t pci_mcfg_lookup(u16 seg, struct resource *bus_res)
+int pci_mcfg_lookup(struct acpi_pci_root *root, struct resource *cfgres,
+		    struct pci_ecam_ops **ecam_ops)
 {
+	struct pci_ecam_ops *ops = &pci_generic_ecam_ops;
+	struct resource *bus_res = &root->secondary;
+	u16 seg = root->segment;
 	struct mcfg_entry *e;
+	struct resource res;
+
+	/* Use address from _CBA if present, otherwise lookup MCFG */
+	if (root->mcfg_addr)
+		goto skip_lookup;
 
 	/*
 	 * We expect exact match, unless MCFG entry end bus covers more than
@@ -45,10 +55,22 @@ phys_addr_t pci_mcfg_lookup(u16 seg, struct resource *bus_res)
 	 */
 	list_for_each_entry(e, &pci_mcfg_list, list) {
 		if (e->segment == seg && e->bus_start == bus_res->start &&
-		    e->bus_end >= bus_res->end)
-			return e->addr;
+		    e->bus_end >= bus_res->end) {
+			root->mcfg_addr = e->addr;
+		}
+
 	}
 
+	if (!root->mcfg_addr)
+		return -ENXIO;
+
+skip_lookup:
+	memset(&res, 0, sizeof(res));
+	res.start = root->mcfg_addr + (bus_res->start << 20);
+	res.end = res.start + (resource_size(bus_res) << 20) - 1;
+	res.flags = IORESOURCE_MEM;
+	*cfgres = res;
+	*ecam_ops = ops;
 	return 0;
 }
 
diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
index 7d63a66e8ed4..7a4e83a8c89c 100644
--- a/include/linux/pci-acpi.h
+++ b/include/linux/pci-acpi.h
@@ -24,7 +24,9 @@ static inline acpi_status pci_acpi_remove_pm_notifier(struct acpi_device *dev)
 }
 extern phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle);
 
-extern phys_addr_t pci_mcfg_lookup(u16 domain, struct resource *bus_res);
+struct pci_ecam_ops;
+extern int pci_mcfg_lookup(struct acpi_pci_root *root, struct resource *cfgres,
+			   struct pci_ecam_ops **ecam_ops);
 
 static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
 {