xHCI: Correct the #define XHCI_LEGACY_DISABLE_SMI

Re-define XHCI_LEGACY_DISABLE_SMI and used it in right way. All SMI enable
bits will be cleared to zero and flag bits 29:31 are also cleared to zero.
Other bits should be presvered as Table 146.

This patch should be backported to kernels as old as 2.6.31.
Signed-off-by: Alex He <alex.he@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org

drivers/usb/host/pci-quirks.c

@@ -825,9 +825,13 @@ static void __devinit quirk_usb_handoff_xhci(struct pci_dev *pdev)
 		}
 	}
 
-	/* Disable any BIOS SMIs */
-	writel(XHCI_LEGACY_DISABLE_SMI,
-			base + ext_cap_offset + XHCI_LEGACY_CONTROL_OFFSET);
+	val = readl(base + ext_cap_offset + XHCI_LEGACY_CONTROL_OFFSET);
+	/* Mask off (turn off) any enabled SMIs */
+	val &= XHCI_LEGACY_DISABLE_SMI;
+	/* Mask all SMI events bits, RW1C */
+	val |= XHCI_LEGACY_SMI_EVENTS;
+	/* Disable any BIOS SMIs and clear all SMI events*/
+	writel(val, base + ext_cap_offset + XHCI_LEGACY_CONTROL_OFFSET);
 
 	if (usb_is_intel_switchable_xhci(pdev))
 		usb_enable_xhci_ports(pdev);

drivers/usb/host/xhci-ext-caps.h

@@ -62,8 +62,9 @@
 /* USB Legacy Support Control and Status Register  - section 7.1.2 */
 /* Add this offset, plus the value of xECP in HCCPARAMS to the base address */
 #define XHCI_LEGACY_CONTROL_OFFSET	(0x04)
-/* bits 1:2, 5:12, and 17:19 need to be preserved; bits 21:28 should be zero */
-#define	XHCI_LEGACY_DISABLE_SMI		((0x3 << 1) + (0xff << 5) + (0x7 << 17))
+/* bits 1:3, 5:12, and 17:19 need to be preserved; bits 21:28 should be zero */
+#define	XHCI_LEGACY_DISABLE_SMI		((0x7 << 1) + (0xff << 5) + (0x7 << 17))
+#define XHCI_LEGACY_SMI_EVENTS		(0x7 << 29)
 
 /* USB 2.0 xHCI 0.96 L1C capability - section 7.2.2.1.3.2 */
 #define XHCI_L1C               (1 << 16)