Commit e82cc128 authored by David Brownell's avatar David Brownell Committed by Greg Kroah-Hartman
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USB: fix ehci unlink regressions 



The recent EHCI driver update to split the IAA watchdog timer out from
the other timers made several things work better, but not everything;
and it created a couple new issues in bugzilla.  Ergo this patch:

  - Handle a should-be-rare SMP race between the watchdog firing
    and (very late) IAA interrupts;

  - Remove a shouldn't-have-been-added WARN_ON() test;

  - Guard against one observed OOPS;

  - If this watchdog fires during clean HC shutdown, it should act
    as a NOP instead of interfering with the shutdown sequence;

  - Guard against silicon errata hypothesized by some vendors:
      * IAA status latch broken, but IAAD cleared OK;
      * IAAD wasn't cleared when IAA status got reported;

The WARN_ON is in bugzilla as 10168; the OOPS as 10078; these are
both regressions.

Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Tested-by: default avatarGordon Farquharson <gordonfarquharson@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 11171d1b

drivers/usb/host/ehci-hcd.c

+46 −16
Original line number Diff line number Diff line
@@ -281,23 +281,44 @@ static void ehci_iaa_watchdog(unsigned long param) 
{

	struct ehci_hcd		*ehci = (struct ehci_hcd *) param;

	unsigned long		flags;

	u32			status, cmd;



	spin_lock_irqsave (&ehci->lock, flags);

	WARN_ON(!ehci->reclaim);



	status = ehci_readl(ehci, &ehci->regs->status);

	/* 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->reclaim

			&& !timer_pending(&ehci->iaa_watchdog)

			&& HC_IS_RUNNING(ehci_to_hcd(ehci)->state)) {

		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);

	ehci_dbg(ehci, "IAA watchdog: status %x cmd %x\n", status, cmd);



	/* lost IAA irqs wedge things badly; seen first with a vt8235 */

	if (ehci->reclaim) {

		if (status & STS_IAA) {

			ehci_vdbg (ehci, "lost IAA\n");

		if (cmd & CMD_IAAD)

			ehci_writel(ehci, cmd & ~CMD_IAAD,

					&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_writel(ehci, cmd & ~CMD_IAAD, &ehci->regs->command);



		ehci_vdbg(ehci, "IAA watchdog: status %x cmd %x\n",

				status, cmd);

		end_unlink_async(ehci);

	}
@@ -631,7 +652,7 @@ static int ehci_run (struct usb_hcd *hcd) 
static irqreturn_t ehci_irq (struct usb_hcd *hcd)

{

	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);

	u32			status, pcd_status = 0;

	u32			status, pcd_status = 0, cmd;

	int			bh;



	spin_lock (&ehci->lock);
@@ -652,7 +673,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd) 


	/* clear (just) interrupts */

	ehci_writel(ehci, status, &ehci->regs->status);

	ehci_readl(ehci, &ehci->regs->command);	/* unblock posted write */

	cmd = ehci_readl(ehci, &ehci->regs->command);

	bh = 0;



#ifdef	EHCI_VERBOSE_DEBUG
@@ -673,8 +694,17 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd) 


	/* complete the unlinking of some qh [4.15.2.3] */

	if (status & STS_IAA) {

		/* guard against (alleged) silicon errata */

		if (cmd & CMD_IAAD) {

			ehci_writel(ehci, cmd & ~CMD_IAAD,

					&ehci->regs->command);

			ehci_dbg(ehci, "IAA with IAAD still set?\n");

		}

		if (ehci->reclaim) {

			COUNT(ehci->stats.reclaim);

			end_unlink_async(ehci);

		} else

			ehci_dbg(ehci, "IAA with nothing to reclaim?\n");

	}



	/* remote wakeup [4.3.1] */
@@ -781,7 +811,7 @@ static int ehci_urb_enqueue ( 
static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)

{

	/* failfast */

	if (!HC_IS_RUNNING(ehci_to_hcd(ehci)->state))

	if (!HC_IS_RUNNING(ehci_to_hcd(ehci)->state) && ehci->reclaim)

		end_unlink_async(ehci);



	/* if it's not linked then there's nothing to do */

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