diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index c4bb261c106e16eaeab09092a9942418dba61133..8379c2c3d076e8d2a7ee44c580af7fa06ad71d86 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -65,21 +65,16 @@ pcibios_align_resource(void *data, const struct resource *res,
 			resource_size_t size, resource_size_t align)
 {
 	struct pci_dev *dev = data;
-	resource_size_t start = round_down(res->end - size + 1, align);
+	resource_size_t start = res->start;
 
 	if (res->flags & IORESOURCE_IO) {
-
-		/*
-		 * If we're avoiding ISA aliases, the largest contiguous I/O
-		 * port space is 256 bytes.  Clearing bits 9 and 10 preserves
-		 * all 256-byte and smaller alignments, so the result will
-		 * still be correctly aligned.
-		 */
-		if (!skip_isa_ioresource_align(dev))
-			start &= ~0x300;
+		if (skip_isa_ioresource_align(dev))
+			return start;
+		if (start & 0x300)
+			start = (start + 0x3ff) & ~0x3ff;
 	} else if (res->flags & IORESOURCE_MEM) {
 		if (start < BIOS_END)
-			start = res->end;	/* fail; no space */
+			start = BIOS_END;
 	}
 	return start;
 }