diff --git a/drivers/usb/host/ehci-orion.c b/drivers/usb/host/ehci-orion.c
index 1d283e1..0f87dc7 100644
--- a/drivers/usb/host/ehci-orion.c
+++ b/drivers/usb/host/ehci-orion.c
@@ -222,14 +222,14 @@
 		goto err1;
 	}
 
-	if (!request_mem_region(res->start, res->end - res->start + 1,
+	if (!request_mem_region(res->start, resource_size(res),
 				ehci_orion_hc_driver.description)) {
 		dev_dbg(&pdev->dev, "controller already in use\n");
 		err = -EBUSY;
 		goto err1;
 	}
 
-	regs = ioremap(res->start, res->end - res->start + 1);
+	regs = ioremap(res->start, resource_size(res));
 	if (regs == NULL) {
 		dev_dbg(&pdev->dev, "error mapping memory\n");
 		err = -EFAULT;
@@ -244,7 +244,7 @@
 	}
 
 	hcd->rsrc_start = res->start;
-	hcd->rsrc_len = res->end - res->start + 1;
+	hcd->rsrc_len = resource_size(res);
 	hcd->regs = regs;
 
 	ehci = hcd_to_ehci(hcd);
@@ -287,7 +287,7 @@
 err3:
 	iounmap(regs);
 err2:
-	release_mem_region(res->start, res->end - res->start + 1);
+	release_mem_region(res->start, resource_size(res));
 err1:
 	dev_err(&pdev->dev, "init %s fail, %d\n",
 		dev_name(&pdev->dev), err);