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authorAlan Stern <stern@rowland.harvard.edu>2012-07-11 11:22:44 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-07-16 16:56:46 -0700
commit9d9387475af261949f61a5ec465e1f762d7be08a (patch)
tree7aa6688962bde78fba655b791612e60cc1b50adf /drivers/usb/host/ehci-timer.c
parent8c5bf7be56f1a8aecc1f802f132d53f556a9bc45 (diff)
downloadlinux-stericsson-9d9387475af261949f61a5ec465e1f762d7be08a.tar.gz
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: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/host/ehci-timer.c')
-rw-r--r--drivers/usb/host/ehci-timer.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index 8feb60ff4228..aab042064226 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -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 */
};