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>

1 files changed, 1 insertions, 12 deletions

diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 08637183aad0..254f414bd0bd 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -88,6 +88,7 @@ enum ehci_hrtimer_event {
         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 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       watchdog;
-        unsigned long           actions;
         unsigned                random_frame;
         unsigned long           next_statechange;
         ktime_t                 last_periodic_enable;
@@ -235,16 +234,6 @@ static inline struct usb_hcd *ehci_to_hcd (struct ehci_hcd *ehci)
         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>