USB: EHCI: use hrtimer for the I/O watchdog
This patch (as1586) replaces the kernel timer used by ehci-hcd as an
I/O watchdog with an hrtimer event.
Unlike in the current code, the watchdog event is now always enabled
whenever any isochronous URBs are active. This will prevent bugs
caused by the periodic schedule wrapping around with no completion
interrupts; the watchdog handler is guaranteed to scan the isochronous
transfers at least once during each iteration of the schedule. The
extra overhead will be negligible: one timer interrupt every 100 ms.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index c13dad8..9f26080 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -93,8 +93,6 @@
*/
#define EHCI_TUNE_FLS 1 /* (medium) 512-frame schedule */
-#define EHCI_IO_JIFFIES (HZ/10) /* io watchdog > irq_thresh */
-
/* Initial IRQ latency: faster than hw default */
static int log2_irq_thresh = 0; // 0 to 6
module_param (log2_irq_thresh, int, S_IRUGO);
@@ -125,25 +123,6 @@
/*-------------------------------------------------------------------------*/
-static void
-timer_action(struct ehci_hcd *ehci, enum ehci_timer_action action)
-{
- if (!test_and_set_bit(action, &ehci->actions)) {
- unsigned long t;
-
- switch (action) {
- case TIMER_IO_WATCHDOG:
- if (!ehci->need_io_watchdog)
- return;
- t = EHCI_IO_JIFFIES;
- break;
- }
- mod_timer(&ehci->watchdog, t + jiffies);
- }
-}
-
-/*-------------------------------------------------------------------------*/
-
/*
* handshake - spin reading hc until handshake completes or fails
* @ptr: address of hc register to be read
@@ -307,19 +286,6 @@
/*-------------------------------------------------------------------------*/
-static void ehci_watchdog(unsigned long param)
-{
- struct ehci_hcd *ehci = (struct ehci_hcd *) param;
- unsigned long flags;
-
- spin_lock_irqsave(&ehci->lock, flags);
-
- /* ehci could run by timer, without IRQs ... */
- ehci_work (ehci);
-
- spin_unlock_irqrestore (&ehci->lock, flags);
-}
-
/* On some systems, leaving remote wakeup enabled prevents system shutdown.
* The firmware seems to think that powering off is a wakeup event!
* This routine turns off remote wakeup and everything else, on all ports.
@@ -357,8 +323,6 @@
{
struct ehci_hcd *ehci = hcd_to_ehci(hcd);
- del_timer_sync(&ehci->watchdog);
-
spin_lock_irq(&ehci->lock);
ehci->rh_state = EHCI_RH_STOPPING;
ehci_silence_controller(ehci);
@@ -394,8 +358,6 @@
*/
static void ehci_work (struct ehci_hcd *ehci)
{
- timer_action_done (ehci, TIMER_IO_WATCHDOG);
-
/* another CPU may drop ehci->lock during a schedule scan while
* it reports urb completions. this flag guards against bogus
* attempts at re-entrant schedule scanning.
@@ -422,10 +384,7 @@
* misplace IRQs, and should let us run completely without IRQs.
* such lossage has been observed on both VT6202 and VT8235.
*/
- if (ehci->rh_state == EHCI_RH_RUNNING &&
- (ehci->async->qh_next.ptr != NULL ||
- ehci->periodic_count != 0))
- timer_action (ehci, TIMER_IO_WATCHDOG);
+ turn_on_io_watchdog(ehci);
}
/*
@@ -438,7 +397,6 @@
ehci_dbg (ehci, "stop\n");
/* no more interrupts ... */
- del_timer_sync (&ehci->watchdog);
spin_lock_irq(&ehci->lock);
ehci->enabled_hrtimer_events = 0;
@@ -490,9 +448,6 @@
* keep io watchdog by default, those good HCDs could turn off it later
*/
ehci->need_io_watchdog = 1;
- init_timer(&ehci->watchdog);
- ehci->watchdog.function = ehci_watchdog;
- ehci->watchdog.data = (unsigned long) ehci;
hrtimer_init(&ehci->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
ehci->hrtimer.function = ehci_hrtimer_func;
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 5d84562..05490d3 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -208,7 +208,6 @@
if (time_before (jiffies, ehci->next_statechange))
msleep(5);
- del_timer_sync(&ehci->watchdog);
spin_lock_irq (&ehci->lock);
@@ -316,10 +315,6 @@
ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
spin_unlock_irq (&ehci->lock);
- /* ehci_work() may have re-enabled the watchdog timer, which we do not
- * want, and so we must delete any pending watchdog timer events.
- */
- del_timer_sync(&ehci->watchdog);
hrtimer_cancel(&ehci->hrtimer);
return 0;
}
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index c9c7f7b..9bc39ca 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -970,6 +970,7 @@
/* Don't start the schedule until ASS is 0 */
ehci_poll_ASS(ehci);
+ turn_on_io_watchdog(ehci);
}
static void disable_async(struct ehci_hcd *ehci)
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 263b542..26ce8fe 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -489,6 +489,7 @@
/* Don't start the schedule until PSS is 0 */
ehci_poll_PSS(ehci);
+ turn_on_io_watchdog(ehci);
}
static void disable_periodic(struct ehci_hcd *ehci)
@@ -1649,7 +1650,6 @@
iso_sched_free (stream, iso_sched);
urb->hcpriv = NULL;
- timer_action (ehci, TIMER_IO_WATCHDOG);
++ehci->isoc_count;
enable_periodic(ehci);
}
@@ -2052,7 +2052,6 @@
iso_sched_free (stream, sched);
urb->hcpriv = NULL;
- timer_action (ehci, TIMER_IO_WATCHDOG);
++ehci->isoc_count;
enable_periodic(ehci);
}
diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index 0e28bae7..eb896a2 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -76,6 +76,7 @@
10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IAA_WATCHDOG */
10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_PERIODIC */
15 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_ASYNC */
+ 100 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IO_WATCHDOG */
};
/* Enable a pending hrtimer event */
@@ -332,6 +333,25 @@
}
+/* Enable the I/O watchdog, if appropriate */
+static void turn_on_io_watchdog(struct ehci_hcd *ehci)
+{
+ /* Not needed if the controller isn't running or it's already enabled */
+ if (ehci->rh_state != EHCI_RH_RUNNING ||
+ (ehci->enabled_hrtimer_events &
+ BIT(EHCI_HRTIMER_IO_WATCHDOG)))
+ return;
+
+ /*
+ * Isochronous transfers always need the watchdog.
+ * For other sorts we use it only if the flag is set.
+ */
+ if (ehci->isoc_count > 0 || (ehci->need_io_watchdog &&
+ ehci->async_count + ehci->intr_count > 0))
+ ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true);
+}
+
+
/*
* Handler functions for the hrtimer event types.
* Keep this array in the same order as the event types indexed by
@@ -347,6 +367,7 @@
ehci_iaa_watchdog, /* EHCI_HRTIMER_IAA_WATCHDOG */
ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */
ehci_disable_ASE, /* EHCI_HRTIMER_DISABLE_ASYNC */
+ ehci_work, /* EHCI_HRTIMER_IO_WATCHDOG */
};
static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 0863718..254f414 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -88,6 +88,7 @@
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_IO_WATCHDOG, /* Check for missing IRQs */
EHCI_HRTIMER_NUM_EVENTS /* Must come last */
};
#define EHCI_HRTIMER_NO_EVENT 99
@@ -177,8 +178,6 @@
struct dma_pool *itd_pool; /* itd per iso urb */
struct dma_pool *sitd_pool; /* sitd per split iso urb */
- struct timer_list watchdog;
- unsigned long actions;
unsigned random_frame;
unsigned long next_statechange;
ktime_t last_periodic_enable;
@@ -235,16 +234,6 @@
return container_of ((void *) ehci, struct usb_hcd, hcd_priv);
}
-enum ehci_timer_action {
- TIMER_IO_WATCHDOG,
-};
-
-static inline void
-timer_action_done (struct ehci_hcd *ehci, enum ehci_timer_action action)
-{
- clear_bit (action, &ehci->actions);
-}
-
/*-------------------------------------------------------------------------*/
#include <linux/usb/ehci_def.h>