From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [Fwd: 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 11:20:37 -0700 Message-ID: <878whm8dfu.fsf@deeprootsystems.com> References: <4A85A18F.4040207@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-px0-f196.google.com ([209.85.216.196]:54250 "EHLO mail-px0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753424AbZHNSUj (ORCPT ); Fri, 14 Aug 2009 14:20:39 -0400 Received: by pxi34 with SMTP id 34so411421pxi.4 for ; Fri, 14 Aug 2009 11:20:40 -0700 (PDT) In-Reply-To: <4A85A18F.4040207@ti.com> (Jon Hunter's message of "Fri\, 14 Aug 2009 12\:40\:31 -0500") Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Jon Hunter Cc: "linux-omap@vger.kernel.org" Jon Hunter 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@suse.de > To: Hunter, Jon , fei.yang@motorola.com > , gregkh@suse.de , > greg@kroah.com , stern@rowland.harvard.edu > > > > 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@rowland.harvard.edu Thu Aug 13 16:37:16 2009 > From: Jon Hunter > 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 , Jon Hunter > Cc: Fei Yang > Message-ID: > > > From: Jon Hunter > > 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 > > --- > 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@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html