From: gradator@gradator.net (Sylvain Rochet)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 5/6] watchdog: at91sam9: request the irq with IRQF_NO_SUSPEND
Date: Sat, 7 Mar 2015 12:46:08 +0100 [thread overview]
Message-ID: <20150307114608.GA30011@gradator.net> (raw)
In-Reply-To: <20150307112932.GA1372@amd>
Hello,
On Sat, Mar 07, 2015 at 12:29:33PM +0100, Pavel Machek wrote:
> On Sat 2015-03-07 12:06:45, Alexandre Belloni wrote:
> > 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.
>
> Well, it boils down to "what is stronger". Desire to suspend the
> system, or desire to reboot the system.
>
> It is "echo mem > state", not "echo reboot > state".
Maybe we should warn the watchdog is enabled and the system is going to
reboot if nothing woke-up the system before the watchdog expire, but the
maximum watchdog is 16s so it can't get unnoticed during development, I
am confident embedded engineers are smart enough to understand what is
happening without a displayed warning :-)
> > It is documented in the datasheet and any user wanting another behaviour
> > is out of luck.
>
> Actaully, your platform should just refuse to enter suspend-to-RAM
> when hw watchdog is enabled.
Yeah that's what I said, hardware watchdog or suspend: chose one or use
the software watchdog instead or "hack" around the way I am doing ;-)
Sylvain
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next prev parent reply other threads:[~2015-03-07 11:46 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
2015-03-07 11:29 ` Pavel Machek
2015-03-07 11:46 ` Sylvain Rochet [this message]
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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