[PATCH 5/8] usb: xhci: wait for CNR controller not ready bit in xhci resume

[Mathias Nyman <mathias.nyman@linux.intel.com>]

From: Rick Tseng <rtseng@nvidia.com>

NVIDIA 3.1 xHCI card would lose power when moving power state into D3Cold.
Thus we need to wait for CNR bit to clear in xhci resume, just as in
xhci init.

[Minor changes to comment and commit message -Mathias]
Cc: <stable@vger.kernel.org>
Signed-off-by: Rick Tseng <rtseng@nvidia.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index aec69d294973..fe8f9ff58015 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1108,6 +1108,18 @@ int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
 		hibernated = true;
 
 	if (!hibernated) {
+		/*
+		 * Some controllers might lose power during suspend, so wait
+		 * for controller not ready bit to clear, just as in xHC init.
+		 */
+		retval = xhci_handshake(&xhci->op_regs->status,
+					STS_CNR, 0, 10 * 1000 * 1000);
+		if (retval) {
+			xhci_warn(xhci, "Controller not ready at resume %d\n",
+				  retval);
+			spin_unlock_irq(&xhci->lock);
+			return retval;
+		}
 		/* step 1: restore register */
 		xhci_restore_registers(xhci);
 		/* step 2: initialize command ring buffer */
-- 
2.7.4