6 files changed, 84 insertions, 3 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 387cedf2b698..7ad9ef8aedee 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -487,6 +487,7 @@ static int ehci_init(struct usb_hcd *hcd)
         ehci->periodic_size = DEFAULT_I_TDPS;
         INIT_LIST_HEAD(&ehci->async_unlink);
         INIT_LIST_HEAD(&ehci->async_idle);
+        INIT_LIST_HEAD(&ehci->intr_unlink_wait);
         INIT_LIST_HEAD(&ehci->intr_unlink);
         INIT_LIST_HEAD(&ehci->intr_qh_list);
         INIT_LIST_HEAD(&ehci->cached_itd_list);
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 6e69ee1a3371..269a2e8ad0ab 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -345,6 +345,7 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
 
         end_unlink_async(ehci);
         unlink_empty_async_suspended(ehci);
+        ehci_handle_start_intr_unlinks(ehci);
         ehci_handle_intr_unlinks(ehci);
         end_free_itds(ehci);
 
diff --git a/drivers/usb/host/ehci-mem.c b/drivers/usb/host/ehci-mem.c
index ef2c3a1eca4b..52a77734a225 100644
--- a/drivers/usb/host/ehci-mem.c
+++ b/drivers/usb/host/ehci-mem.c
@@ -93,6 +93,7 @@ static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd *ehci, gfp_t flags)
         qh->qh_dma = dma;
         // INIT_LIST_HEAD (&qh->qh_list);
         INIT_LIST_HEAD (&qh->qtd_list);
+        INIT_LIST_HEAD(&qh->unlink_node);
 
         /* dummy td enables safe urb queuing */
         qh->dummy = ehci_qtd_alloc (ehci, flags);
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index f80d0330d548..94388738a6f7 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -601,12 +601,29 @@ static void qh_unlink_periodic(struct ehci_hcd *ehci, struct ehci_qh *qh)
         list_del(&qh->intr_node);
 }
 
+static void cancel_unlink_wait_intr(struct ehci_hcd *ehci, struct ehci_qh *qh)
+{
+        if (qh->qh_state != QH_STATE_LINKED ||
+                        list_empty(&qh->unlink_node))
+                return;
+
+        list_del_init(&qh->unlink_node);
+
+        /*
+         * TODO: disable the event of EHCI_HRTIMER_START_UNLINK_INTR for
+         * avoiding unnecessary CPU wakeup
+         */
+}
+
 static void start_unlink_intr(struct ehci_hcd *ehci, struct ehci_qh *qh)
 {
         /* If the QH isn't linked then there's nothing we can do. */
         if (qh->qh_state != QH_STATE_LINKED)
                 return;
 
+        /* if the qh is waiting for unlink, cancel it now */
+        cancel_unlink_wait_intr(ehci, qh);
+
         qh_unlink_periodic (ehci, qh);
 
         /* Make sure the unlinks are visible before starting the timer */
@@ -632,6 +649,27 @@ static void start_unlink_intr(struct ehci_hcd *ehci, struct ehci_qh *qh)
         }
 }
 
+/*
+ * It is common only one intr URB is scheduled on one qh, and
+ * given complete() is run in tasklet context, introduce a bit
+ * delay to avoid unlink qh too early.
+ */
+static void start_unlink_intr_wait(struct ehci_hcd *ehci,
+                                   struct ehci_qh *qh)
+{
+        qh->unlink_cycle = ehci->intr_unlink_wait_cycle;
+
+        /* New entries go at the end of the intr_unlink_wait list */
+        list_add_tail(&qh->unlink_node, &ehci->intr_unlink_wait);
+
+        if (ehci->rh_state < EHCI_RH_RUNNING)
+                ehci_handle_start_intr_unlinks(ehci);
+        else if (ehci->intr_unlink_wait.next == &qh->unlink_node) {
+                ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true);
+                ++ehci->intr_unlink_wait_cycle;
+        }
+}
+
 static void end_unlink_intr(struct ehci_hcd *ehci, struct ehci_qh *qh)
 {
         struct ehci_qh_hw       *hw = qh->hw;
@@ -889,6 +927,9 @@ static int intr_submit (
         if (qh->qh_state == QH_STATE_IDLE) {
                 qh_refresh(ehci, qh);
                 qh_link_periodic(ehci, qh);
+        } else {
+                /* cancel unlink wait for the qh */
+                cancel_unlink_wait_intr(ehci, qh);
         }
 
         /* ... update usbfs periodic stats */
@@ -924,9 +965,11 @@ static void scan_intr(struct ehci_hcd *ehci)
                          * in qh_unlink_periodic().
                          */
                         temp = qh_completions(ehci, qh);
-                        if (unlikely(temp || (list_empty(&qh->qtd_list) &&
-                                        qh->qh_state == QH_STATE_LINKED)))
+                        if (unlikely(temp))
                                 start_unlink_intr(ehci, qh);
+                        else if (unlikely(list_empty(&qh->qtd_list) &&
+                                        qh->qh_state == QH_STATE_LINKED))
+                                start_unlink_intr_wait(ehci, qh);
                 }
         }
 }
diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index 11e5b32f73e9..424ac5d83714 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -72,6 +72,7 @@ static unsigned event_delays_ns[] = {
         1 * NSEC_PER_MSEC,      /* EHCI_HRTIMER_POLL_DEAD */
         1125 * NSEC_PER_USEC,   /* EHCI_HRTIMER_UNLINK_INTR */
         2 * NSEC_PER_MSEC,      /* EHCI_HRTIMER_FREE_ITDS */
+        5 * NSEC_PER_MSEC,      /* EHCI_HRTIMER_START_UNLINK_INTR */
         6 * NSEC_PER_MSEC,      /* EHCI_HRTIMER_ASYNC_UNLINKS */
         10 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_IAA_WATCHDOG */
         10 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_PERIODIC */
@@ -215,6 +216,36 @@ static void ehci_handle_controller_death(struct ehci_hcd *ehci)
         /* Not in process context, so don't try to reset the controller */
 }
 
+/* start to unlink interrupt QHs  */
+static void ehci_handle_start_intr_unlinks(struct ehci_hcd *ehci)
+{
+        bool            stopped = (ehci->rh_state < EHCI_RH_RUNNING);
+
+        /*
+         * Process all the QHs on the intr_unlink list that were added
+         * before the current unlink cycle began.  The list is in
+         * temporal order, so stop when we reach the first entry in the
+         * current cycle.  But if the root hub isn't running then
+         * process all the QHs on the list.
+         */
+        while (!list_empty(&ehci->intr_unlink_wait)) {
+                struct ehci_qh  *qh;
+
+                qh = list_first_entry(&ehci->intr_unlink_wait,
+                                struct ehci_qh, unlink_node);
+                if (!stopped && (qh->unlink_cycle ==
+                                ehci->intr_unlink_wait_cycle))
+                        break;
+                list_del_init(&qh->unlink_node);
+                start_unlink_intr(ehci, qh);
+        }
+
+        /* Handle remaining entries later */
+        if (!list_empty(&ehci->intr_unlink_wait)) {
+                ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true);
+                ++ehci->intr_unlink_wait_cycle;
+        }
+}
 
 /* Handle unlinked interrupt QHs once they are gone from the hardware */
 static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
@@ -236,7 +267,7 @@ static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
                                 unlink_node);
                 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
                         break;
-                list_del(&qh->unlink_node);
+                list_del_init(&qh->unlink_node);
                 end_unlink_intr(ehci, qh);
         }
 
@@ -363,6 +394,7 @@ static void (*event_handlers[])(struct ehci_hcd *) = {
         ehci_handle_controller_death,   /* EHCI_HRTIMER_POLL_DEAD */
         ehci_handle_intr_unlinks,       /* EHCI_HRTIMER_UNLINK_INTR */
         end_free_itds,                  /* EHCI_HRTIMER_FREE_ITDS */
+        ehci_handle_start_intr_unlinks, /* EHCI_HRTIMER_START_UNLINK_INTR */
         unlink_empty_async,             /* EHCI_HRTIMER_ASYNC_UNLINKS */
         ehci_iaa_watchdog,              /* EHCI_HRTIMER_IAA_WATCHDOG */
         ehci_disable_PSE,               /* EHCI_HRTIMER_DISABLE_PERIODIC */
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 64f9a08e959c..947752015d5d 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -88,6 +88,7 @@ enum ehci_hrtimer_event {
         EHCI_HRTIMER_POLL_DEAD,         /* Wait for dead controller to stop */
         EHCI_HRTIMER_UNLINK_INTR,       /* Wait for interrupt QH unlink */
         EHCI_HRTIMER_FREE_ITDS,         /* Wait for unused iTDs and siTDs */
+        EHCI_HRTIMER_START_UNLINK_INTR, /* Unlink empty interrupt QHs */
         EHCI_HRTIMER_ASYNC_UNLINKS,     /* Unlink empty async QHs */
         EHCI_HRTIMER_IAA_WATCHDOG,      /* Handle lost IAA interrupts */
         EHCI_HRTIMER_DISABLE_PERIODIC,  /* Wait to disable periodic sched */
@@ -143,7 +144,9 @@ struct ehci_hcd {			/* one per controller */
         unsigned                i_thresh;       /* uframes HC might cache */
 
         union ehci_shadow       *pshadow;       /* mirror hw periodic table */
+        struct list_head        intr_unlink_wait;
         struct list_head        intr_unlink;
+        unsigned                intr_unlink_wait_cycle;
         unsigned                intr_unlink_cycle;
         unsigned                now_frame;      /* frame from HC hardware */
         unsigned                last_iso_frame; /* last frame scanned for iso */