diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index 744aa7fc49d5..76b8cd953dee 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -201,6 +201,12 @@ struct chipset {
 	void (*f)(int num, int slot, int func);
 };
 
+/*
+ * Only works for devices on the root bus. If you add any devices
+ * not on bus 0 readd another loop level in early_quirks(). But
+ * be careful because at least the Nvidia quirk here relies on
+ * only matching on bus 0.
+ */
 static struct chipset early_qrk[] __initdata = {
 	{ PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID,
 	  PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, QFLAG_APPLY_ONCE, nvidia_bugs },
@@ -267,17 +273,17 @@ static int __init check_dev_quirk(int num, int slot, int func)
 
 void __init early_quirks(void)
 {
-	int num, slot, func;
+	int slot, func;
 
 	if (!early_pci_allowed())
 		return;
 
 	/* Poor man's PCI discovery */
-	for (num = 0; num < 32; num++)
-		for (slot = 0; slot < 32; slot++)
-			for (func = 0; func < 8; func++) {
-				/* Only probe function 0 on single fn devices */
-				if (check_dev_quirk(num, slot, func))
-					break;
-			}
+	/* Only scan the root bus */
+	for (slot = 0; slot < 32; slot++)
+		for (func = 0; func < 8; func++) {
+			/* Only probe function 0 on single fn devices */
+			if (check_dev_quirk(0, slot, func))
+				break;
+		}
 }