USB: Set wakeup bits for all children hubs.

This patch takes care of the race condition between the Function Wake
Device Notification and the auto-suspend timeout for this situation:

Roothub
  | (U3)
hub A
  | (U3)
hub B
  | (U3)
device C

When device C signals a resume, the xHCI driver will set the wakeup_bits
for the roothub port that hub A is attached to.  However, since USB 3.0
hubs do not set a link state change bit on device-initiated resume, hub
A will not indicate a port event when polled.  Without this patch, khubd
will notice the wakeup-bits are set for the roothub port, it will resume
hub A, and then it will poll the events bits for hub A and notice that
nothing has changed.  Then it will be suspended after 2 seconds.

Change hub_activate() to look at the port link state for each USB 3.0
hub port, and set hub->change_bits if the link state is U0, indicating
the device has finished resume.  Change the resume function called by
hub_events(), hub_handle_remote_wakeup(), to check the link status
for resume instead of just the port's wakeup_bits.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 1c32bba..994aa88 100644 (file)
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -853,12 +853,19 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
                                set_bit(port1, hub->change_bits);
 
                } else if (portstatus & USB_PORT_STAT_ENABLE) {
+                       bool port_resumed = (portstatus &
+                                       USB_PORT_STAT_LINK_STATE) ==
+                               USB_SS_PORT_LS_U0;
                        /* The power session apparently survived the resume.
                         * If there was an overcurrent or suspend change
                         * (i.e., remote wakeup request), have khubd
-                        * take care of it.
+                        * take care of it.  Look at the port link state
+                        * for USB 3.0 hubs, since they don't have a suspend
+                        * change bit, and they don't set the port link change
+                        * bit on device-initiated resume.
                         */
-                       if (portchange)
+                       if (portchange || (hub_is_superspeed(hub->hdev) &&
+                                               port_resumed))
                                set_bit(port1, hub->change_bits);
 
                } else if (udev->persist_enabled) {
@@ -3509,7 +3516,7 @@ done:
 
 /* Returns 1 if there was a remote wakeup and a connect status change. */
 static int hub_handle_remote_wakeup(struct usb_hub *hub, unsigned int port,
-               u16 portchange)
+               u16 portstatus, u16 portchange)
 {
        struct usb_device *hdev;
        struct usb_device *udev;
@@ -3524,8 +3531,8 @@ static int hub_handle_remote_wakeup(struct usb_hub *hub, unsigned int port,
                clear_port_feature(hdev, port, USB_PORT_FEAT_C_SUSPEND);
        } else {
                if (!udev || udev->state != USB_STATE_SUSPENDED ||
-                               !test_and_clear_bit(udev->portnum,
-                                       hub->wakeup_bits))
+                                (portstatus & USB_PORT_STAT_LINK_STATE) !=
+                                USB_SS_PORT_LS_U0)
                        return 0;
        }
 
@@ -3638,7 +3645,7 @@ static void hub_events(void)
                        if (test_bit(i, hub->busy_bits))
                                continue;
                        connect_change = test_bit(i, hub->change_bits);
-                       wakeup_change = test_bit(i, hub->wakeup_bits);
+                       wakeup_change = test_and_clear_bit(i, hub->wakeup_bits);
                        if (!test_and_clear_bit(i, hub->event_bits) &&
                                        !connect_change && !wakeup_change)
                                continue;
@@ -3681,7 +3688,8 @@ static void hub_events(void)
                                }
                        }
 
-                       if (hub_handle_remote_wakeup(hub, i, portchange))
+                       if (hub_handle_remote_wakeup(hub, i,
+                                               portstatus, portchange))
                                connect_change = 1;
 
                        if (portchange & USB_PORT_STAT_C_OVERCURRENT) {