From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from oul135-36.netplaza.fi ([80.75.100.36]:38380 "EHLO lime.offcode.fi" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751637AbaKLIVD (ORCPT ); Wed, 12 Nov 2014 03:21:03 -0500 Message-ID: <54631869.9070709@offcode.fi> Date: Wed, 12 Nov 2014 10:20:57 +0200 From: Timo Kokkonen MIME-Version: 1.0 To: linux-arm-kernel@lists.infradead.org, linux-watchdog@vger.kernel.org Subject: Re: [PATCH] at91sam9_wdt: Allow watchdog to reset device at early boot References: <1414060846-17306-1-git-send-email-timo.kokkonen@offcode.fi> In-Reply-To: <1414060846-17306-1-git-send-email-timo.kokkonen@offcode.fi> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org Hi, On 10/23/14 13:40, Timo Kokkonen wrote: > By default the driver will start a kernel timer which keeps on kicking > the watchdog HW until user space has opened the watchdog > device. Usually this is desirable as the watchdog HW is running by > default and the user space may not have any watchdog daemon running at > all. > > However, on production systems it may be mandatory that also early > crashes and lockups will lead to a watchdog reset, even if they happen > before the user space has opened the watchdog device. > > To resolve the issue, add a new device tree property > "atmel,no-early-timer" which will prevent the kernel timer from > pinging the watchdog HW on behalf of user space. The default is still > to use kernel timer, but more strict behavior can be enabled via the > device tree property. > Any thoughts on this one? Should I resend this with some more people or lists to get someone to comment or review this patch? Thanks, -Timo > Signed-off-by: Timo Kokkonen > --- > Documentation/devicetree/bindings/watchdog/atmel-wdt.txt | 4 ++++ > drivers/watchdog/at91sam9_wdt.c | 6 +++++- > 2 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt b/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt > index f90e294..1b9289e 100644 > --- a/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt > +++ b/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt > @@ -28,6 +28,10 @@ Optional properties: > entering idle state. > - atmel,dbg-halt : Should be present if you want to stop the watchdog when > entering debug state. > +- atmel,no-early-timer : Should be present if you want to let the > + watchdog timer to expire even before user space has opened the > + device. If not set, a kernel timer will keep on pinging the > + watchdog until it is opened. > > Example: > watchdog@fffffd40 { > diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c > index 489729b..8cac712 100644 > --- a/drivers/watchdog/at91sam9_wdt.c > +++ b/drivers/watchdog/at91sam9_wdt.c > @@ -89,6 +89,7 @@ struct at91wdt { > u32 mr_mask; > unsigned long heartbeat; /* WDT heartbeat in jiffies */ > bool nowayout; > + bool no_early_timer; > unsigned int irq; > }; > > @@ -122,7 +123,7 @@ static void at91_ping(unsigned long data) > { > struct at91wdt *wdt = (struct at91wdt *)data; > if (time_before(jiffies, wdt->next_heartbeat) || > - !watchdog_active(&wdt->wdd)) { > + (!watchdog_active(&wdt->wdd) && !wdt->no_early_timer)) { > at91_wdt_reset(wdt); > mod_timer(&wdt->timer, jiffies + wdt->heartbeat); > } else { > @@ -316,6 +317,9 @@ static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt) > > wdt->mr |= max | ((max - min) << 16); > > + if (of_property_read_bool(np, "atmel,no-early-timer")) > + wdt->no_early_timer = 1; > + > return 0; > } > #else >