diff options
Diffstat (limited to 'drivers/usb/host/ehci-hcd.c')
| -rw-r--r-- | drivers/usb/host/ehci-hcd.c | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index 099aff64f536..566badb05b34 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; } |