diff options
| author | Jon Hunter <jon-hunter@ti.com> | 2009-08-12 11:57:59 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-09-23 06:46:33 -0700 |
| commit | 015798b2f166725b1dae2b07b5ffb127ab187be0 (patch) | |
| tree | 8e737d2a85ba93bbe135051c426993f9cc272f2a | |
| parent | 0ffd3b2902e28b13d8379df0f09a55668f330f77 (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>
| -rw-r--r-- | 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 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; } |