From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ezequiel Garcia Subject: Re: [PATCH v6 05/19] watchdog: orion: Make sure the watchdog is initially stopped Date: Fri, 7 Feb 2014 07:40:45 -0300 Message-ID: <20140207104044.GA11063@localhost> References: <1391707226-18258-1-git-send-email-ezequiel.garcia@free-electrons.com> <1391707226-18258-6-git-send-email-ezequiel.garcia@free-electrons.com> <52F43ED0.4050808@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <52F43ED0.4050808-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Guenter Roeck , Jason Gunthorpe Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Wim Van Sebroeck , Jason Cooper , Thomas Petazzoni , Gregory Clement , Lior Amsalem , Sebastian Hesselbarth , Andrew Lunn List-Id: devicetree@vger.kernel.org On Thu, Feb 06, 2014 at 06:02:56PM -0800, Guenter Roeck wrote: > On 02/06/2014 09:20 AM, Ezequiel Garcia wrote: > > Having the watchdog initially fully stopped is important to avoid > > any spurious watchdog triggers, in case the registers are not in > > its reset state. > > > > Reviewed-by: Guenter Roeck > > Tested-by: Sebastian Hesselbarth > > Tested-by: Willy Tarreau > > Signed-off-by: Ezequiel Garcia > > --- > > drivers/watchdog/orion_wdt.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/watchdog/orion_wdt.c b/drivers/watchdog/orion_= wdt.c > > index 6746033..2dbeee9 100644 > > --- a/drivers/watchdog/orion_wdt.c > > +++ b/drivers/watchdog/orion_wdt.c > > @@ -142,6 +142,9 @@ static int orion_wdt_probe(struct platform_devi= ce *pdev) > > orion_wdt.max_timeout =3D wdt_max_duration; > > watchdog_init_timeout(&orion_wdt, heartbeat, &pdev->dev); > > > > + /* Let's make sure the watchdog is fully stopped */ > > + orion_wdt_stop(&orion_wdt); > > + >=20 > Actually we just had that in another driver, and I stumbled over it t= here. >=20 > Problem with stopping the watchdog in probe unconditionally is that y= ou can > use it to defeat nowayout: unload the module, then load it again, > and the watchdog is stopped even if nowayout is true. >=20 Hm... I see. > Is this really what you want ? Or, in other words, what is the proble= m > you are trying to solve ? >=20 Well, this is related to the discussion about the bootloader not reseting the watchdog properly, provoking spurious watchdog triggering. Jason Gunthorpe explained [1] that we needed a particular sequence: 1. Disable WDT 2. Clear bridge 3. Enable WDT We added the irq handling to satisfy (2), and the watchdog stop for (1)= =2E The watchdog stop was agreed specifically [2]. Ideas? [1] http://www.spinics.net/lists/arm-kernel/msg302340.html [2] http://www.spinics.net/lists/arm-kernel/msg302507.html --=20 Ezequiel Garc=C3=ADa, Free Electrons Embedded Linux, Kernel and Android Engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html