[3.5.y.z extended stable] Patch "usb: hub: Clear Port Reset Change during init/resume" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Tue Nov 19 13:17:45 UTC 2013

This is a note to let you know that I have just added a patch titled

    usb: hub: Clear Port Reset Change during init/resume

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From 9ac0c5f84940e2ee260b25751ce5d650cfe1cdba Mon Sep 17 00:00:00 2001
From: Julius Werner <jwerner at chromium.org>
Date: Tue, 15 Oct 2013 17:45:00 -0700
Subject: usb: hub: Clear Port Reset Change during init/resume

commit e92aee330837e4911553761490a8fb843f2053a6 upstream.

This patch adds the Port Reset Change flag to the set of bits that are
preemptively cleared on init/resume of a hub. In theory this bit should
never be set unexpectedly... in practice it can still happen if BIOS,
SMM or ACPI code plays around with USB devices without cleaning up
correctly. This is especially dangerous for XHCI root hubs, which don't
generate any more Port Status Change Events until all change bits are
cleared, so this is a good precaution to have (similar to how it's
already done for the Warm Port Reset Change flag).

Signed-off-by: Julius Werner <jwerner at chromium.org>
Acked-by: Alan Stern <stern at rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
[ luis: backported to 3.5:
  - adjusted context
  - replaced usb_clear_port_feature() by clear_port_feature() ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 drivers/usb/core/hub.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 86c7421..b5503b0 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1142,6 +1142,11 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
 			clear_port_feature(hub->hdev, port1,
+		if (portchange & USB_PORT_STAT_C_RESET) {
+			need_debounce_delay = true;
+			clear_port_feature(hub->hdev, port1,
+		}
 		if ((portchange & USB_PORT_STAT_C_BH_RESET) &&
 				hub_is_superspeed(hub->hdev)) {
 			need_debounce_delay = true;

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