USB: EHCI update VIA workaround

This revamps handling of the hardware "async advance" IRQ, and its watchdog
timer.  Basically it dis-entangles that important timeout from the others,
simplifying the associated state and code to make it more robust.

This reportedly improves behavior of EHCI on some systems with VIA chips,
and AFAIK won't affect non-VIA hardware.  VIA systems need this code to
recover from silcon bugs whereby the "async advance" IRQ isn't issued.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 50 insertions, 23 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 4e1a8c30889..5ac91859113 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -111,7 +111,7 @@ static const char	hcd_name [] = "ehci_hcd";
 #define	EHCI_TUNE_MULT_TT	1
 #define	EHCI_TUNE_FLS		2	/* (small) 256 frame schedule */
 
-#define EHCI_IAA_JIFFIES	(HZ/100)	/* arbitrary; ~10 msec */
+#define EHCI_IAA_MSECS		10		/* arbitrary */
 #define EHCI_IO_JIFFIES		(HZ/10)		/* io watchdog > irq_thresh */
 #define EHCI_ASYNC_JIFFIES	(HZ/20)		/* async idle timeout */
 #define EHCI_SHRINK_JIFFIES	(HZ/200)	/* async qh unlink delay */
@@ -254,6 +254,7 @@ static void ehci_quiesce (struct ehci_hcd *ehci)
 
 /*-------------------------------------------------------------------------*/
 
+static void end_unlink_async (struct ehci_hcd *ehci, struct pt_regs *regs);
 static void ehci_work(struct ehci_hcd *ehci, struct pt_regs *regs);
 
 #include "ehci-hub.c"
@@ -263,28 +264,39 @@ static void ehci_work(struct ehci_hcd *ehci, struct pt_regs *regs);
 
 /*-------------------------------------------------------------------------*/
 
-static void ehci_watchdog (unsigned long param)
+static void ehci_iaa_watchdog (unsigned long param)
 {
 	struct ehci_hcd		*ehci = (struct ehci_hcd *) param;
 	unsigned long		flags;
+	u32			status;
 
 	spin_lock_irqsave (&ehci->lock, flags);
+	WARN_ON(!ehci->reclaim);
 
-	/* lost IAA irqs wedge things badly; seen with a vt8235 */
+	/* lost IAA irqs wedge things badly; seen first with a vt8235 */
 	if (ehci->reclaim) {
-		u32		status = readl (&ehci->regs->status);
-
+		status = readl (&ehci->regs->status);
 		if (status & STS_IAA) {
 			ehci_vdbg (ehci, "lost IAA\n");
 			COUNT (ehci->stats.lost_iaa);
 			writel (STS_IAA, &ehci->regs->status);
-			ehci->reclaim_ready = 1;
+			end_unlink_async (ehci, NULL);
 		}
 	}
 
- 	/* stop async processing after it's idled a bit */
+	spin_unlock_irqrestore (&ehci->lock, flags);
+}
+
+static void ehci_watchdog (unsigned long param)
+{
+	struct ehci_hcd		*ehci = (struct ehci_hcd *) param;
+	unsigned long		flags;
+
+	spin_lock_irqsave (&ehci->lock, flags);
+
+	/* stop async processing after it's idled a bit */
 	if (test_bit (TIMER_ASYNC_OFF, &ehci->actions))
- 		start_unlink_async (ehci, ehci->async);
+		start_unlink_async (ehci, ehci->async);
 
 	/* ehci could run by timer, without IRQs ... */
 	ehci_work (ehci, NULL);
@@ -333,8 +345,6 @@ static void ehci_port_power (struct ehci_hcd *ehci, int is_on)
 static void ehci_work (struct ehci_hcd *ehci, struct pt_regs *regs)
 {
 	timer_action_done (ehci, TIMER_IO_WATCHDOG);
-	if (ehci->reclaim_ready)
-		end_unlink_async (ehci, regs);
 
 	/* another CPU may drop ehci->lock during a schedule scan while
 	 * it reports urb completions.  this flag guards against bogus
@@ -369,6 +379,7 @@ 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);
 	if (HC_IS_RUNNING (hcd->state))
@@ -415,6 +426,10 @@ 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;
+
 	/*
 	 * hw default: 1K periodic list heads, one per frame.
 	 * periodic_size can shrink by USBCMD update if hcc_params allows.
@@ -431,7 +446,6 @@ static int ehci_init(struct usb_hcd *hcd)
 		ehci->i_thresh = 2 + HCC_ISOC_THRES(hcc_params);
 
 	ehci->reclaim = NULL;
-	ehci->reclaim_ready = 0;
 	ehci->next_uframe = -1;
 
 	/*
@@ -605,7 +619,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd, struct pt_regs *regs)
 	/* complete the unlinking of some qh [4.15.2.3] */
 	if (status & STS_IAA) {
 		COUNT (ehci->stats.reclaim);
-		ehci->reclaim_ready = 1;
+		end_unlink_async (ehci, regs);
 		bh = 1;
 	}
 
@@ -709,10 +723,14 @@ static int ehci_urb_enqueue (
 
 static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 {
-	/* if we need to use IAA and it's busy, defer */
-	if (qh->qh_state == QH_STATE_LINKED
-			&& ehci->reclaim
-			&& HC_IS_RUNNING (ehci_to_hcd(ehci)->state)) {
+	// BUG_ON(qh->qh_state != QH_STATE_LINKED);
+
+	/* failfast */
+	if (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
+		end_unlink_async (ehci, NULL);
+
+	/* defer till later if busy */
+	else if (ehci->reclaim) {
 		struct ehci_qh		*last;
 
 		for (last = ehci->reclaim;
@@ -722,12 +740,8 @@ static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 		qh->qh_state = QH_STATE_UNLINK_WAIT;
 		last->reclaim = qh;
 
-	/* bypass IAA if the hc can't care */
-	} else if (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state) && ehci->reclaim)
-		end_unlink_async (ehci, NULL);
-
-	/* something else might have unlinked the qh by now */
-	if (qh->qh_state == QH_STATE_LINKED)
+	/* start IAA cycle */
+	} else
 		start_unlink_async (ehci, qh);
 }
 
@@ -749,7 +763,19 @@ static int ehci_urb_dequeue (struct usb_hcd *hcd, struct urb *urb)
 		qh = (struct ehci_qh *) urb->hcpriv;
 		if (!qh)
 			break;
-		unlink_async (ehci, qh);
+		switch (qh->qh_state) {
+		case QH_STATE_LINKED:
+		case QH_STATE_COMPLETING:
+			unlink_async (ehci, qh);
+			break;
+		case QH_STATE_UNLINK:
+		case QH_STATE_UNLINK_WAIT:
+			/* already started */
+			break;
+		case QH_STATE_IDLE:
+			WARN_ON(1);
+			break;
+		}
 		break;
 
 	case PIPE_INTERRUPT:
@@ -841,6 +867,7 @@ rescan:
 		unlink_async (ehci, qh);
 		/* FALL THROUGH */
 	case QH_STATE_UNLINK:		/* wait for hw to finish? */
+	case QH_STATE_UNLINK_WAIT:
 idle_timeout:
 		spin_unlock_irqrestore (&ehci->lock, flags);
 		schedule_timeout_uninterruptible(1);