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Commit 9d938747 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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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: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8c5bf7be

drivers/usb/host/ehci-hcd.c

+14 −52
Original line number Diff line number Diff line
@@ -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");

drivers/usb/host/ehci-hub.c

+0 −1
Original line number Diff line number Diff line
@@ -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);

drivers/usb/host/ehci-q.c

+1 −3
Original line number Diff line number Diff line
@@ -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);

}



/*-------------------------------------------------------------------------*/

drivers/usb/host/ehci-timer.c

+45 −0
Original line number Diff line number Diff line
@@ -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 */

};

drivers/usb/host/ehci.h

+1 −15
Original line number Diff line number Diff line
@@ -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,