Patch "xhci: prevent bus_suspend if SS port resuming in phase 1" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

xhci: prevent bus_suspend if SS port resuming in phase 1

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xhci-prevent-bus_suspend-if-ss-port-resuming-in-phase-1.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Zhuang Jin Can <[email protected]>
Date: Tue, 21 Jul 2015 17:20:30 +0300
Subject: xhci: prevent bus_suspend if SS port resuming in phase 1

From: Zhuang Jin Can <[email protected]>

commit fac4271d1126c45ceaceb7f4a336317b771eb121 upstream.

When the link is just waken, it's in Resume state, and driver sets PLS to U0. This refers to Phase 1. Phase 2 refers to when the link has completed the transition from Resume state to U0.

With the fix of xhci: report U3 when link is in resume state, it also exposes an issue that usb3 roothub and controller can suspend right after phase 1, and this causes a hard hang in controller.

To fix the issue, we need to prevent usb3 bus suspend if any port is resuming in phase 1.

---
 drivers/usb/host/xhci-hub.c  |    6 +++---
 drivers/usb/host/xhci-ring.c |    3 +++
 drivers/usb/host/xhci.h      |    1 +
 3 files changed, 7 insertions(+), 3 deletions(-)

@@ -1123,10 +1123,10 @@ int xhci_bus_suspend(struct usb_hcd *hcd
 	spin_lock_irqsave(&xhci->lock, flags);
 
 	if (hcd->self.root_hub->do_remote_wakeup) {
-		if (bus_state->resuming_ports) {
+		if (bus_state->resuming_ports ||	/* USB2 */
+		    bus_state->port_remote_wakeup) {	/* USB3 */
 			spin_unlock_irqrestore(&xhci->lock, flags);
-			xhci_dbg(xhci, "suspend failed because "
-						"a port is resuming\n");
+			xhci_dbg(xhci, "suspend failed because a port is resuming\n");
 			return -EBUSY;
 		}
 	}

@@ -1546,6 +1546,9 @@ static void handle_port_status(struct xh
 		usb_hcd_resume_root_hub(hcd);
 	}
 
+	if (hcd->speed == HCD_USB3 && (temp & PORT_PLS_MASK) == XDEV_INACTIVE)
+		bus_state->port_remote_wakeup &= ~(1 << faked_port_index);
+
 	if ((temp & PORT_PLC) && (temp & PORT_PLS_MASK) == XDEV_RESUME) {
 		xhci_dbg(xhci, "port resume event for port %d\n", port_id);
 

@@ -285,6 +285,7 @@ struct xhci_op_regs {
 #define XDEV_U0		(0x0 << 5)
 #define XDEV_U2		(0x2 << 5)
 #define XDEV_U3		(0x3 << 5)
+#define XDEV_INACTIVE	(0x6 << 5)
 #define XDEV_RESUME	(0xf << 5)
 /* true: port has power (see HCC_PPC) */
 #define PORT_POWER	(1 << 9)

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/xhci-do-not-report-plc-when-link-is-in-internal-resume-state.patch queue-4.1/xhci-prevent-bus_suspend-if-ss-port-resuming-in-phase-1.patch queue-4.1/xhci-report-u3-when-link-is-in-resume-state.patch