From: Jon Hunter Date: Wed, 12 Aug 2009 15:57:59 +0000 (-0400) Subject: USB: EHCI: ensure all watchdog timer events are deleted when suspending usb X-Git-Tag: v2.6.32-rc1~174^2~60 X-Git-Url: http://ftp.safe.ca/?a=commitdiff_plain;ds=sidebyside;h=015798b2f166725b1dae2b07b5ffb127ab187be0;p=safe%2Fjmp%2Flinux-2.6 USB: EHCI: ensure all watchdog timer events are deleted when suspending usb 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 Signed-off-by: Jon Hunter Acked-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c index 6fef1ee..818647c 100644 --- a/drivers/usb/host/ehci-hub.c +++ b/drivers/usb/host/ehci-hub.c @@ -209,6 +209,11 @@ 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; }