diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c
index a8e91ae..ffc2874 100644
--- a/arch/x86/lib/delay.c
+++ b/arch/x86/lib/delay.c
@@ -168,6 +168,36 @@ inline void __const_udelay(unsigned long xloops)
 }
 EXPORT_SYMBOL(__const_udelay);
 
+void udelay_uninitialized(unsigned long xloops)
+{
+	unsigned long lpj = (1<<12);
+	int d0;
+
+	xloops *= 0x10c7ul;
+	xloops *= 4;
+	asm("mull %%edx"
+		:"=d" (xloops), "=&a" (d0)
+		:"1" (xloops), "0" (lpj * (HZ / 4)));
+
+	delay_loop(++xloops);
+}
+EXPORT_SYMBOL(udelay_uninitialized);
+
+void udelay_initialized(unsigned long xloops)
+{
+	unsigned long lpj = this_cpu_read(cpu_info.loops_per_jiffy);
+	int d0;
+
+	xloops *= 0x10c7ul;
+	xloops *= 4;
+	asm("mull %%edx"
+		:"=d" (xloops), "=&a" (d0)
+		:"1" (xloops), "0" (lpj * (HZ / 4)));
+
+	delay_loop(++xloops);
+}
+EXPORT_SYMBOL(udelay_initialized);
+
 void __udelay(unsigned long usecs)
 {
 	__const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 954abfd..b6a7437 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -302,6 +302,21 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	/* USB-2 and USB-3 roothubs initialized, allow runtime pm suspend */
 	pm_runtime_put_noidle(&dev->dev);
 
+	do {
+		int count = 1000;
+
+		pr_notice("udelay_test uninitialized ---->start\n");
+		while (count-- > 0)
+			udelay_uninitialized(100);
+		pr_notice("udelay_test uninitialized ---->end\n");
+
+		count = 1000;
+		pr_notice("udelay_test initialized ---->start\n");
+		while (count-- > 0)
+			udelay_initialized(100);
+		pr_notice("udelay_test initialized ---->end\n");
+	} while (0);
+
 	return 0;
 
 put_usb3_hcd:
diff --git a/include/asm-generic/delay.h b/include/asm-generic/delay.h
index 0f79054..200ab55 100644
--- a/include/asm-generic/delay.h
+++ b/include/asm-generic/delay.h
@@ -9,6 +9,8 @@ extern void __udelay(unsigned long usecs);
 extern void __ndelay(unsigned long nsecs);
 extern void __const_udelay(unsigned long xloops);
 extern void __delay(unsigned long loops);
+extern void udelay_uninitialized(unsigned long xloops);
+extern void udelay_initialized(unsigned long xloops);
 
 /*
  * The weird n/20000 thing suppresses a "comparison is always false due to