[PATCH 3.5 42/78] usb: hub: Clear Port Reset Change during init/resume

Luis Henriques luis.henriques at canonical.com
Mon Nov 25 13:06:29 UTC 2013 -stable review patch.  If anyone has any objections, please let me know.


From: Julius Werner <jwerner at chromium.org>

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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