usb: hub: avoid warm port reset during USB3 disconnect

During disconnect USB-3 ports often go via SS.Inactive link error state
before the missing terminations are noticed, and link finally goes to
RxDetect state

Avoid immediately warm-resetting ports in SS.Inactive state.
Let ports settle for a while and re-read the link status a few times 20ms
apart to see if the ports transitions out of SS.Inactive.

According to USB 3.x spec 7.5.2, a port in SS.Inactive should
automatically check for missing far-end receiver termination every
12 ms (SSInactiveQuietTimeout)

The futile multiple warm reset retries of a disconnected device takes
a lot of time, also the resetting of a removed devices has caused cases
where the reset bit got stuck for a long time on xHCI roothub.
This lead to issues in detecting new devices connected to the same port
shortly after.

Tested-by: Mark Pearson <markpearson@lenovo.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20211210111653.1378381-1-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 00070a8..e907dfa 100644 (file)
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2777,6 +2777,8 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
 #define PORT_INIT_TRIES                4
 #endif /* CONFIG_USB_FEW_INIT_RETRIES */
 
+#define DETECT_DISCONNECT_TRIES 5
+
 #define HUB_ROOT_RESET_TIME    60      /* times are in msec */
 #define HUB_SHORT_RESET_TIME   10
 #define HUB_BH_RESET_TIME      50
@@ -5543,6 +5545,7 @@ static void port_event(struct usb_hub *hub, int port1)
        struct usb_device *udev = port_dev->child;
        struct usb_device *hdev = hub->hdev;
        u16 portstatus, portchange;
+       int i = 0;
 
        connect_change = test_bit(port1, hub->change_bits);
        clear_bit(port1, hub->event_bits);
@@ -5619,17 +5622,27 @@ static void port_event(struct usb_hub *hub, int port1)
                connect_change = 1;
 
        /*
-        * Warm reset a USB3 protocol port if it's in
-        * SS.Inactive state.
+        * Avoid trying to recover a USB3 SS.Inactive port with a warm reset if
+        * the device was disconnected. A 12ms disconnect detect timer in
+        * SS.Inactive state transitions the port to RxDetect automatically.
+        * SS.Inactive link error state is common during device disconnect.
         */
-       if (hub_port_warm_reset_required(hub, port1, portstatus)) {
-               dev_dbg(&port_dev->dev, "do warm reset\n");
-               if (!udev || !(portstatus & USB_PORT_STAT_CONNECTION)
+       while (hub_port_warm_reset_required(hub, port1, portstatus)) {
+               if ((i++ < DETECT_DISCONNECT_TRIES) && udev) {
+                       u16 unused;
+
+                       msleep(20);
+                       hub_port_status(hub, port1, &portstatus, &unused);
+                       dev_dbg(&port_dev->dev, "Wait for inactive link disconnect detect\n");
+                       continue;
+               } else if (!udev || !(portstatus & USB_PORT_STAT_CONNECTION)
                                || udev->state == USB_STATE_NOTATTACHED) {
+                       dev_dbg(&port_dev->dev, "do warm reset, port only\n");
                        if (hub_port_reset(hub, port1, NULL,
                                        HUB_BH_RESET_TIME, true) < 0)
                                hub_port_disable(hub, port1, 1);
                } else {
+                       dev_dbg(&port_dev->dev, "do warm reset, full device\n");
                        usb_unlock_port(port_dev);
                        usb_lock_device(udev);
                        usb_reset_device(udev);
@@ -5637,6 +5650,7 @@ static void port_event(struct usb_hub *hub, int port1)
                        usb_lock_port(port_dev);
                        connect_change = 0;
                }
+               break;
        }
 
        if (connect_change)