From: Alexandre Belloni <alexandre.belloni@free-electrons.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Sylvain Rochet <gradator@gradator.net>,
Peter Zijlstra <peterz@infradead.org>,
Mark Rutland <mark.rutland@arm.com>,
Boris Brezillon <boris.brezillon@free-electrons.com>,
Alessandro Zummo <a.zummo@towertech.it>,
Mike Turquette <mturquette@linaro.org>,
Jason Cooper <jason@lakedaemon.net>,
"rtc-linux@googlegroups.com" <rtc-linux@googlegroups.com>,
Len Brown <len.brown@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Nicolas Ferre <nicolas.ferre@atmel.com>,
Wim Van Sebroeck <wim@iguana.be>,
"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>,
Thomas Gleixner <tglx@linutronix.de>, Jiri Slaby <jslaby@suse.cz>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>
Subject: Re: [PATCH v2 5/6] watchdog: at91sam9: request the irq with IRQF_NO_SUSPEND
Date: Sat, 7 Mar 2015 12:06:45 +0100 [thread overview]
Message-ID: <20150307110645.GW3989@piout.net> (raw)
In-Reply-To: <20150307103939.GA17964@amd>
On 07/03/2015 at 11:39:39 +0100, Pavel Machek wrote :
> > The Atmel watchdog can't be stopped once it's started. This is actually
> > very useful so we can reset if suspend or resume failed, the only
> > drawback is that you have to wake up from time to time (e.g. by using
> > the RTC/RTT) to clear the watchdog and then go back to sleep ASAP.
>
> Yeah. So you do "echo mem > /sys/power/state", and few seconds/minutes
> after watchdog kills the system. But you did not ask for dead system,
> you asked for suspend.
>
> And while that behaviour is useful for you, I don't think it is
> exactly useful behaviour, nor it is the behaviour user would expect.
>
I think you misunderstood, that is exactly the expected behaviour. This
is hardware defined. Once the watchdog is started, nobody can stop it.
Trying to change the mode register will result in a reset of the SoC.
It is documented in the datasheet and any user wanting another behaviour
is out of luck.
So basically, when using a watchdog, you have to wake up every 15-16s to
restart it.
--
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
next prev parent reply other threads:[~2015-03-07 11:06 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-02 9:18 [PATCH v2 0/6] ARM: at91: fix irq_pm_install_action WARNING Boris Brezillon
2015-03-02 9:18 ` [PATCH v2 1/6] PM / wakeup: export pm_system_wakeup symbol Boris Brezillon
2015-03-02 9:18 ` [PATCH v2 2/6] rtc: at91sam9: rework wakeup and interrupt handling Boris Brezillon
2015-03-04 18:23 ` Mark Rutland
2015-03-02 9:18 ` [PATCH v2 3/6] rtc: at91rm9200: " Boris Brezillon
2015-03-02 9:18 ` [PATCH v2 4/6] clk: at91: implement suspend/resume for the PMC irqchip Boris Brezillon
2015-03-09 22:34 ` Mike Turquette
2015-03-02 9:18 ` [PATCH v2 5/6] watchdog: at91sam9: request the irq with IRQF_NO_SUSPEND Boris Brezillon
2015-03-02 14:10 ` Guenter Roeck
2015-03-04 18:38 ` Mark Rutland
2015-03-04 21:41 ` Rafael J. Wysocki
2015-03-05 10:57 ` Mark Rutland
2015-03-05 15:10 ` Rafael J. Wysocki
2015-03-05 16:32 ` Mark Rutland
2015-03-06 0:29 ` Rafael J. Wysocki
2015-03-06 11:06 ` Mark Rutland
2015-03-06 12:39 ` Rafael J. Wysocki
2015-03-06 13:10 ` Mark Rutland
2015-03-07 9:12 ` Peter Zijlstra
2015-03-07 9:06 ` Peter Zijlstra
2015-03-05 8:53 ` Boris Brezillon
2015-03-05 10:53 ` Mark Rutland
2015-03-05 11:17 ` Boris Brezillon
2015-03-05 11:31 ` Boris Brezillon
2015-03-05 11:53 ` Mark Rutland
2015-03-07 9:18 ` Peter Zijlstra
2015-03-07 10:20 ` Sylvain Rochet
2015-03-07 10:39 ` Pavel Machek
2015-03-07 10:59 ` Sylvain Rochet
2015-03-07 11:06 ` Alexandre Belloni [this message]
2015-03-07 11:29 ` Pavel Machek
2015-03-07 11:46 ` Sylvain Rochet
2015-03-08 1:12 ` Rafael J. Wysocki
2015-03-09 7:55 ` Alexandre Belloni
2015-03-09 14:30 ` Rafael J. Wysocki
2015-03-10 21:33 ` Alexandre Belloni
2015-03-10 22:31 ` Rafael J. Wysocki
2015-03-10 22:33 ` Alexandre Belloni
2015-03-11 1:03 ` Rafael J. Wysocki
2015-03-11 7:33 ` Boris Brezillon
2015-03-08 1:11 ` Rafael J. Wysocki
2015-03-11 8:38 ` Boris Brezillon
2015-03-11 11:17 ` Nicolas Ferre
2015-03-02 9:18 ` [PATCH v2 6/6] tty: serial: atmel: rework interrupt and wakeup handling Boris Brezillon
2015-03-03 8:56 ` [PATCH v2 0/6] ARM: at91: fix irq_pm_install_action WARNING Alexandre Belloni
2015-03-03 15:35 ` Nicolas Ferre
2015-03-04 1:43 ` Rafael J. Wysocki
2015-03-04 18:43 ` Mark Rutland
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