Jon Hunter <jon-hunter@xxxxxx> writes: > Hi All, > > I just thought I would send out this patch as an FYI. We recently ran > into an issue where we were getting a kernel panic in the ehci driver > when entering suspend on the omap3. We discussed this with the > linux-usb folks and they recommended the below fix. This problem is > hard to reproduce, but has not been seen since adding this fix. Anyway > the details are below. > Jon, Do you know if this will be queued as a fix for .31? or if it will wait for the .32 merge window. Kevin > > -------- Original Message -------- > Subject: patch > usb-ehci-ensure-all-watchdog-timer-events-are-deleted-when-suspending-usb.patch > added to gregkh-2.6 tree > Date: Fri, 14 Aug 2009 11:48:45 -0500 > From: gregkh@xxxxxxx <gregkh@xxxxxxx> > To: Hunter, Jon <jon-hunter@xxxxxx>, fei.yang@xxxxxxxxxxxx > <fei.yang@xxxxxxxxxxxx>, gregkh@xxxxxxx <gregkh@xxxxxxx>, > greg@xxxxxxxxx <greg@xxxxxxxxx>, stern@xxxxxxxxxxxxxxxxxxx > <stern@xxxxxxxxxxxxxxxxxxx> > > > This is a note to let you know that I've just added the patch titled > > Subject: USB: EHCI: ensure all watchdog timer events are deleted > when suspending usb > > to my gregkh-2.6 tree. Its filename is > > > usb-ehci-ensure-all-watchdog-timer-events-are-deleted-when-suspending-usb.patch > > This tree can be found at > > http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/ > > > From stern@xxxxxxxxxxxxxxxxxxx Thu Aug 13 16:37:16 2009 > From: Jon Hunter <jon-hunter@xxxxxx> > Date: Wed, 12 Aug 2009 11:57:59 -0400 (EDT) > Subject: USB: EHCI: ensure all watchdog timer events are deleted when > suspending usb > To: Greg KH <greg@xxxxxxxxx>, Jon Hunter <jon-hunter@xxxxxx> > Cc: Fei Yang <fei.yang@xxxxxxxxxxxx> > Message-ID: <Pine.LNX.4.44L0.0908121157090.9635-100000@xxxxxxxxxxxxxxxxxxxx> > > > 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> > Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx> > > --- > drivers/usb/host/ehci-hub.c | 5 +++++ > 1 file changed, 5 insertions(+) > > --- 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_ > > 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; > } > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-omap" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
