[PATCH] usb: warm reset USB3 ports stuck in polling

[Mathias Nyman]

warm reset USB3 ports stuck in polling after 360ms.

In the polling state USB3 ports are link training, which should
not take longer than 360ms according to USB3 specification
tPollingLFPSTimeout value.

The card reader connected to xhci in MacBookPro is found stuck
in this state after resuming from suspend.

Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
---
 drivers/usb/core/hub.c | 36 +++++++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 8d4631c..448884d 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1151,9 +1151,10 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
 		 */
 		if (hub_is_superspeed(hdev) &&
 		    ((portstatus & USB_PORT_STAT_LINK_STATE) ==
-						USB_SS_PORT_LS_POLLING))
+						USB_SS_PORT_LS_POLLING)) {
 			need_debounce_delay = true;
-
+			set_bit(port1, hub->event_bits);
+		}
 		/* Clear status-change flags; we'll debounce later */
 		if (portchange & USB_PORT_STAT_C_CONNECTION) {
 			need_debounce_delay = true;
@@ -2697,6 +2698,9 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
 #define HUB_LONG_RESET_TIME	200
 #define HUB_RESET_TIMEOUT	800
 
+#define HUB_LFPS_TIME		24
+#define HUB_LFPS_TIMEOUT	360
+
 /*
  * "New scheme" enumeration causes an extra state transition to be
  * exposed to an xhci host and causes USB3 devices to receive control
@@ -2737,6 +2741,31 @@ static bool hub_port_warm_reset_required(struct usb_hub *hub, int port1,
 		|| link_state == USB_SS_PORT_LS_COMP_MOD;
 }
 
+static bool hub_port_stuck_in_polling(struct usb_hub *hub, int port1,
+				      u16 portstatus)
+{
+	u16 link_state;
+	u16 portchange;
+	int lfps_delay = 0;
+
+	if (!hub_is_superspeed(hub->hdev))
+		return false;
+
+	link_state = portstatus & USB_PORT_STAT_LINK_STATE;
+
+	while (link_state == USB_SS_PORT_LS_POLLING) {
+		msleep(HUB_LFPS_TIME);
+
+		hub_port_status(hub, port1, &portstatus, &portchange);
+		link_state = portstatus & USB_PORT_STAT_LINK_STATE;
+
+		lfps_delay += HUB_LFPS_TIME;
+		if (lfps_delay > HUB_LFPS_TIMEOUT)
+			return true;
+	}
+	return false;
+}
+
 static int hub_port_wait_reset(struct usb_hub *hub, int port1,
 			struct usb_device *udev, unsigned int delay, bool warm)
 {
@@ -5329,7 +5358,8 @@ static void port_event(struct usb_hub *hub, int port1)
 	 * Warm reset a USB3 protocol port if it's in
 	 * SS.Inactive state.
 	 */
-	if (hub_port_warm_reset_required(hub, port1, portstatus)) {
+	if (hub_port_warm_reset_required(hub, port1, portstatus) ||
+	    hub_port_stuck_in_polling(hub, port1, portstatus)) {
 		dev_dbg(&port_dev->dev, "do warm reset\n");
 		if (!udev || !(portstatus & USB_PORT_STAT_CONNECTION)
 				|| udev->state == USB_STATE_NOTATTACHED) {
-- 
2.7.4


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