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>

1 files changed, 14 insertions, 52 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");