1 files changed, 67 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 099aff64f53..566badb05b3 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -273,6 +273,58 @@ static void ehci_work(struct ehci_hcd *ehci);
 
 /*-------------------------------------------------------------------------*/
 
+#ifdef CONFIG_CPU_FREQ
+
+#include <linux/cpufreq.h>
+
+static void ehci_cpufreq_pause (struct ehci_hcd *ehci)
+{
+	unsigned long	flags;
+
+	spin_lock_irqsave(&ehci->lock, flags);
+	if (!ehci->cpufreq_changing++)
+		qh_inactivate_split_intr_qhs(ehci);
+	spin_unlock_irqrestore(&ehci->lock, flags);
+}
+
+static void ehci_cpufreq_unpause (struct ehci_hcd *ehci)
+{
+	unsigned long	flags;
+
+	spin_lock_irqsave(&ehci->lock, flags);
+	if (!--ehci->cpufreq_changing)
+		qh_reactivate_split_intr_qhs(ehci);
+	spin_unlock_irqrestore(&ehci->lock, flags);
+}
+
+/*
+ * ehci_cpufreq_notifier is needed to avoid MMF errors that occur when
+ * EHCI controllers that don't cache many uframes get delayed trying to
+ * read main memory during CPU frequency transitions.  This can cause
+ * split interrupt transactions to not be completed in the required uframe.
+ * This has been observed on the Broadcom/ServerWorks HT1000 controller.
+ */
+static int ehci_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
+				 void *data)
+{
+	struct ehci_hcd *ehci = container_of(nb, struct ehci_hcd,
+					     cpufreq_transition);
+
+	switch (val) {
+	case CPUFREQ_PRECHANGE:
+		ehci_cpufreq_pause(ehci);
+		break;
+	case CPUFREQ_POSTCHANGE:
+		ehci_cpufreq_unpause(ehci);
+		break;
+	}
+	return 0;
+}
+
+#endif
+
+/*-------------------------------------------------------------------------*/
+
 static void ehci_watchdog (unsigned long param)
 {
 	struct ehci_hcd		*ehci = (struct ehci_hcd *) param;
@@ -404,6 +456,10 @@ static void ehci_stop (struct usb_hcd *hcd)
 	ehci_writel(ehci, 0, &ehci->regs->intr_enable);
 	spin_unlock_irq(&ehci->lock);
 
+#ifdef CONFIG_CPU_FREQ
+	cpufreq_unregister_notifier(&ehci->cpufreq_transition,
+				    CPUFREQ_TRANSITION_NOTIFIER);
+#endif
 	/* let companion controllers work when we aren't */
 	ehci_writel(ehci, 0, &ehci->regs->configured_flag);
 
@@ -509,6 +565,17 @@ static int ehci_init(struct usb_hcd *hcd)
 	}
 	ehci->command = temp;
 
+#ifdef CONFIG_CPU_FREQ
+	INIT_LIST_HEAD(&ehci->split_intr_qhs);
+	/*
+	 * If the EHCI controller caches enough uframes, this probably
+	 * isn't needed unless there are so many low/full speed devices
+	 * that the controller's can't cache it all.
+	 */
+	ehci->cpufreq_transition.notifier_call = ehci_cpufreq_notifier;
+	cpufreq_register_notifier(&ehci->cpufreq_transition,
+				  CPUFREQ_TRANSITION_NOTIFIER);
+#endif
 	return 0;
 }