USB: EHCI: use hrtimer for the IAA watchdog

This patch (as1581) replaces the iaa_watchdog kernel timer used by
ehci-hcd with an hrtimer event, in keeping with the general conversion
to high-res timers.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

5 files changed, 61 insertions, 71 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index fb1966cf5649..f74ba277c22d 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -93,7 +93,6 @@ static const char	hcd_name [] = "ehci_hcd";
  */
 #define EHCI_TUNE_FLS           1       /* (medium) 512-frame schedule */
 
-#define EHCI_IAA_MSECS          10              /* arbitrary */
 #define EHCI_IO_JIFFIES         (HZ/10)         /* io watchdog > irq_thresh */
 #define EHCI_SHRINK_JIFFIES     (DIV_ROUND_UP(HZ, 200) + 1)
                                                 /* 5-ms async qh unlink delay */
@@ -322,51 +321,6 @@ static void end_unlink_intr(struct ehci_hcd *ehci, struct ehci_qh *qh);
 
 /*-------------------------------------------------------------------------*/
 
-static void ehci_iaa_watchdog(unsigned long param)
-{
-        struct ehci_hcd         *ehci = (struct ehci_hcd *) param;
-        unsigned long           flags;
-
-        spin_lock_irqsave (&ehci->lock, flags);
-
-        /* Lost IAA irqs wedge things badly; seen first with a vt8235.
-         * So we need this watchdog, but must protect it against both
-         * (a) SMP races against real IAA firing and retriggering, and
-         * (b) clean HC shutdown, when IAA watchdog was pending.
-         */
-        if (ehci->async_unlink
-                        && !timer_pending(&ehci->iaa_watchdog)
-                        && ehci->rh_state == EHCI_RH_RUNNING) {
-                u32 cmd, status;
-
-                /* If we get here, IAA is *REALLY* late.  It's barely
-                 * conceivable that the system is so busy that CMD_IAAD
-                 * is still legitimately set, so let's be sure it's
-                 * clear before we read STS_IAA.  (The HC should clear
-                 * CMD_IAAD when it sets STS_IAA.)
-                 */
-                cmd = ehci_readl(ehci, &ehci->regs->command);
-
-                /* If IAA is set here it either legitimately triggered
-                 * before we cleared IAAD above (but _way_ late, so we'll
-                 * still count it as lost) ... or a silicon erratum:
-                 * - VIA seems to set IAA without triggering the IRQ;
-                 * - IAAD potentially cleared without setting IAA.
-                 */
-                status = ehci_readl(ehci, &ehci->regs->status);
-                if ((status & STS_IAA) || !(cmd & CMD_IAAD)) {
-                        COUNT (ehci->stats.lost_iaa);
-                        ehci_writel(ehci, STS_IAA, &ehci->regs->status);
-                }
-
-                ehci_vdbg(ehci, "IAA watchdog: status %x cmd %x\n",
-                                status, cmd);
-                end_unlink_async(ehci);
-        }
-
-        spin_unlock_irqrestore(&ehci->lock, flags);
-}
-
 static void ehci_watchdog(unsigned long param)
 {
         struct ehci_hcd         *ehci = (struct ehci_hcd *) param;
@@ -418,7 +372,6 @@ static void ehci_shutdown(struct usb_hcd *hcd)
         struct ehci_hcd *ehci = hcd_to_ehci(hcd);
 
         del_timer_sync(&ehci->watchdog);
-        del_timer_sync(&ehci->iaa_watchdog);
 
         spin_lock_irq(&ehci->lock);
         ehci->rh_state = EHCI_RH_STOPPING;
@@ -491,7 +444,6 @@ static void ehci_stop (struct usb_hcd *hcd)
 
         /* no more interrupts ... */
         del_timer_sync (&ehci->watchdog);
-        del_timer_sync(&ehci->iaa_watchdog);
 
         spin_lock_irq(&ehci->lock);
         ehci->enabled_hrtimer_events = 0;
@@ -547,10 +499,6 @@ static int ehci_init(struct usb_hcd *hcd)
         ehci->watchdog.function = ehci_watchdog;
         ehci->watchdog.data = (unsigned long) ehci;
 
-        init_timer(&ehci->iaa_watchdog);
-        ehci->iaa_watchdog.function = ehci_iaa_watchdog;
-        ehci->iaa_watchdog.data = (unsigned long) ehci;
-
         hrtimer_init(&ehci->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
         ehci->hrtimer.function = ehci_hrtimer_func;
         ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
@@ -830,6 +778,20 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
 
         /* complete the unlinking of some qh [4.15.2.3] */
         if (status & STS_IAA) {
+
+                /* Turn off the IAA watchdog */
+                ehci->enabled_hrtimer_events &= ~BIT(EHCI_HRTIMER_IAA_WATCHDOG);
+
+                /*
+                 * Mild optimization: Allow another IAAD to reset the
+                 * hrtimer, if one occurs before the next expiration.
+                 * In theory we could always cancel the hrtimer, but
+                 * tests show that about half the time it will be reset
+                 * for some other event anyway.
+                 */
+                if (ehci->next_hrtimer_event == EHCI_HRTIMER_IAA_WATCHDOG)
+                        ++ehci->next_hrtimer_event;
+
                 /* guard against (alleged) silicon errata */
                 if (cmd & CMD_IAAD)
                         ehci_dbg(ehci, "IAA with IAAD still set?\n");
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 6ad806bbe468..3097872b1e74 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -209,7 +209,6 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
         if (time_before (jiffies, ehci->next_statechange))
                 msleep(5);
         del_timer_sync(&ehci->watchdog);
-        del_timer_sync(&ehci->iaa_watchdog);
 
         spin_lock_irq (&ehci->lock);
 
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index d68764ef4476..7b35933d91a6 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -1173,8 +1173,6 @@ static void end_unlink_async (struct ehci_hcd *ehci)
         struct ehci_qh          *qh = ehci->async_unlink;
         struct ehci_qh          *next;
 
-        iaa_watchdog_done(ehci);
-
         // qh->hw_next = cpu_to_hc32(qh->qh_dma);
         qh->qh_state = QH_STATE_IDLE;
         qh->qh_next.qh = NULL;
@@ -1243,7 +1241,7 @@ static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 
         ehci_writel(ehci, ehci->command | CMD_IAAD, &ehci->regs->command);
         (void)ehci_readl(ehci, &ehci->regs->command);
-        iaa_watchdog_start(ehci);
+        ehci_enable_event(ehci, EHCI_HRTIMER_IAA_WATCHDOG, true);
 }
 
 /*-------------------------------------------------------------------------*/
diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index 8feb60ff4228..aab042064226 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 */
+        10 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_IAA_WATCHDOG */
         10 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_PERIODIC */
         15 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_ASYNC */
 };
@@ -291,6 +292,49 @@ static void end_free_itds(struct ehci_hcd *ehci)
 }
 
 
+/* Handle lost (or very late) IAA interrupts */
+static void ehci_iaa_watchdog(struct ehci_hcd *ehci)
+{
+        if (ehci->rh_state != EHCI_RH_RUNNING)
+                return;
+
+        /*
+         * Lost IAA irqs wedge things badly; seen first with a vt8235.
+         * So we need this watchdog, but must protect it against both
+         * (a) SMP races against real IAA firing and retriggering, and
+         * (b) clean HC shutdown, when IAA watchdog was pending.
+         */
+        if (ehci->async_unlink) {
+                u32 cmd, status;
+
+                /* If we get here, IAA is *REALLY* late.  It's barely
+                 * conceivable that the system is so busy that CMD_IAAD
+                 * is still legitimately set, so let's be sure it's
+                 * clear before we read STS_IAA.  (The HC should clear
+                 * CMD_IAAD when it sets STS_IAA.)
+                 */
+                cmd = ehci_readl(ehci, &ehci->regs->command);
+
+                /*
+                 * If IAA is set here it either legitimately triggered
+                 * after the watchdog timer expired (_way_ late, so we'll
+                 * still count it as lost) ... or a silicon erratum:
+                 * - VIA seems to set IAA without triggering the IRQ;
+                 * - IAAD potentially cleared without setting IAA.
+                 */
+                status = ehci_readl(ehci, &ehci->regs->status);
+                if ((status & STS_IAA) || !(cmd & CMD_IAAD)) {
+                        COUNT(ehci->stats.lost_iaa);
+                        ehci_writel(ehci, STS_IAA, &ehci->regs->status);
+                }
+
+                ehci_vdbg(ehci, "IAA watchdog: status %x cmd %x\n",
+                                status, cmd);
+                end_unlink_async(ehci);
+        }
+}
+
+
 /*
  * Handler functions for the hrtimer event types.
  * Keep this array in the same order as the event types indexed by
@@ -302,6 +346,7 @@ 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_iaa_watchdog,              /* EHCI_HRTIMER_IAA_WATCHDOG */
         ehci_disable_PSE,               /* EHCI_HRTIMER_DISABLE_PERIODIC */
         ehci_disable_ASE,               /* EHCI_HRTIMER_DISABLE_ASYNC */
 };
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 755e30b0000b..d9414aae610f 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -84,6 +84,7 @@ 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_IAA_WATCHDOG,      /* Handle lost IAA interrupts */
         EHCI_HRTIMER_DISABLE_PERIODIC,  /* Wait to disable periodic sched */
         EHCI_HRTIMER_DISABLE_ASYNC,     /* Wait to disable async sched */
         EHCI_HRTIMER_NUM_EVENTS         /* Must come last */
@@ -168,7 +169,6 @@ struct ehci_hcd {			/* one per controller */
         struct dma_pool         *itd_pool;      /* itd per iso urb */
         struct dma_pool         *sitd_pool;     /* sitd per split iso urb */
 
-        struct timer_list       iaa_watchdog;
         struct timer_list       watchdog;
         unsigned long           actions;
         unsigned                periodic_stamp;
@@ -228,20 +228,6 @@ static inline struct usb_hcd *ehci_to_hcd (struct ehci_hcd *ehci)
         return container_of ((void *) ehci, struct usb_hcd, hcd_priv);
 }
 
-
-static inline void
-iaa_watchdog_start(struct ehci_hcd *ehci)
-{
-        WARN_ON(timer_pending(&ehci->iaa_watchdog));
-        mod_timer(&ehci->iaa_watchdog,
-                        jiffies + msecs_to_jiffies(EHCI_IAA_MSECS));
-}
-
-static inline void iaa_watchdog_done(struct ehci_hcd *ehci)
-{
-        del_timer(&ehci->iaa_watchdog);
-}
-
 enum ehci_timer_action {
         TIMER_IO_WATCHDOG,
         TIMER_ASYNC_SHRINK,