path: root/drivers/usb/host/ehci-hub.c
diff options
authorJon Hunter <jon-hunter@ti.com>2009-08-12 11:57:59 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2009-09-23 06:46:33 -0700
commit015798b2f166725b1dae2b07b5ffb127ab187be0 (patch)
tree8e737d2a85ba93bbe135051c426993f9cc272f2a /drivers/usb/host/ehci-hub.c
parent0ffd3b2902e28b13d8379df0f09a55668f330f77 (diff)
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 <fei.yang@motorola.com> Signed-off-by: Jon Hunter <jon-hunter@ti.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/host/ehci-hub.c')
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 6fef1ee7d101..818647c33da8 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;