From: Jon Hunter <jon-hunter@xxxxxx> This patch was previously discussed in the following thread: http://thread.gmane.org/gmane.linux.usb.general/19472/focus=19484 On the OMAP3 device the usbhost controller is in a separate internal power-domain. So when the usbhost is inactive or suspend is called, we can disable clocks and power-down the usbhost to save power. Recently we found that after calling ehci_bus_suspend() and disabling the usbhost clocks we would see the ehci watchdog timer event fire. This was causing a kernel panic because the usbhost controllers clocks were disabled and inside the watchdog timer function the clocks were not being re-enabled, so when the ehci registers were accessed this resulted in a CPU data-abort. To avoid this panic, per recommendation from Alan Stern (see above thread), we make sure any pending timer events (that may have been scheduled by calling ehci_work within the ehci_bus_suspend() function) are deleted before returning. Signed-off-by: Fei Yang <fei.yang@xxxxxxxxxxxx> Signed-off-by: Jon Hunter <jon-hunter@xxxxxx> --- drivers/usb/host/ehci-hub.c | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-) diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c index f46ad27..96801ca 100644 --- a/drivers/usb/host/ehci-hub.c +++ b/drivers/usb/host/ehci-hub.c @@ -183,6 +183,11 @@ static int ehci_bus_suspend (struct usb_hcd *hcd) ehci->next_statechange = jiffies + msecs_to_jiffies(10); spin_unlock_irq (&ehci->lock); + + /* ehci_work() may have re-enabled the watchdog timer, which we do not + * want, and so we must delete any pending watchdog timer events. + */ + del_timer_sync(&ehci->watchdog); return 0; } -- 1.6.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
