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USB: fix ehci unlink regressions

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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: David Brownell <dbrownell@users.sourceforge.net>
Tested-by: Gordon Farquharson <gordonfarquharson@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
David Brownell 2008-03-07 13:49:42 -08:00 committed by Greg Kroah-Hartman
parent 11171d1bde
commit e82cc1288f
1 changed files with 45 additions and 15 deletions
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60
drivers/usb/host/ehci-hcd.c
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@ -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);
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.
* 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;
/* 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 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 (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) {
COUNT (ehci->stats.reclaim);
end_unlink_async(ehci);
/* 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 */