From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Rob Herring <robh+dt@kernel.org>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
"open list:REAL TIME CLOCK (RTC) SUBSYSTEM"
<linux-rtc@vger.kernel.org>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Qiang Zhao <qiang.zhao@nxp.com>,
Bruno Thomsen <bruno.thomsen@gmail.com>
Subject: Re: [PATCH v2 1/3] dt-bindings: rtc: add reset-source property
Date: Thu, 17 Dec 2020 19:12:09 +0100 [thread overview]
Message-ID: <20201217181209.sibyhlfvlpjaewrv@pengutronix.de> (raw)
In-Reply-To: <CAL_Jsq+HeeFUR1Yv37X4OnkEPvSiAc2B86=Nshxz7tmvpKk+zw@mail.gmail.com>
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On Thu, Dec 17, 2020 at 10:51:08AM -0600, Rob Herring wrote:
> On Fri, Dec 11, 2020 at 5:10 PM Rasmus Villemoes
> <rasmus.villemoes@prevas.dk> wrote:
> >
> > On 11/12/2020 23.30, Rob Herring wrote:
> > > On Fri, Dec 11, 2020 at 3:56 PM Rasmus Villemoes
> > > <rasmus.villemoes@prevas.dk> wrote:
> > >>
> > >> Some RTCs, e.g. the pcf2127, can be used as a hardware watchdog. But
> > >> if the reset pin is not actually wired up, the driver exposes a
> > >> watchdog device that doesn't actually work.
> > >>
> > >> Provide a standard binding that can be used to indicate that a given
> > >> RTC can perform a reset of the machine, similar to wakeup-source.
> > >
> > > Why not use the watchdog 'timeout-sec' property?
> >
> > Wouldn't that be overloading that property? AFAIU, that is used to ask
> > the kernel to program an initial timeout value into the watchdog device.
> > But what if one doesn't want to start the watchdog device at kernel
> > boot, but just indicate that the RTC has that capability?
>
> Yeah, I guess you're right.
I agree, too. The initial suggestion looks fine.
> > It's quite possible that if it can act as a watchdog device (and
> > has-watchdog was also suggested), one would also want timeout-sec and
> > other watchdog bindings to apply. But that can be added later, by those
> > who actually want that.
> >
> > For now, I'd really like to get my board booting again (or rather, not
> > get reset by the real watchdog just because the pcf2127 driver now
> > exposes something as /dev/wathdog0, pushing the real one to
> > /dev/wathcdog1 which doesn't get pinged from userspace).
>
> I'm wondering how you solve which wdog to ping when there are multiple
> without relying on numbering. I guess 'reset-source' will solve that
> even if that's not your current fix. So I guess I'm fine with this.
I guess you'd need some udev magic that ensures that the right watchdog
always gets the same number.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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next prev parent reply other threads:[~2020-12-17 18:13 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 5:48 [Patch v2 1/3] dt-bindings: rtc: pcf2127: Add bindings for nxp,pcf2127 Qiang Zhao
2020-09-21 5:48 ` [Patch v2 2/3] rtc: pcf2127: add "no-watchdog" property Qiang Zhao
2020-09-21 5:48 ` [Patch v2 3/3] arm64: dts: lx2160a: Add "no-watchdog" property to pcf2127 Qiang Zhao
2020-09-23 9:44 ` [Patch v2 1/3] dt-bindings: rtc: pcf2127: Add bindings for nxp,pcf2127 Alexandre Belloni
2020-09-24 3:20 ` Qiang Zhao
2020-09-24 7:04 ` Uwe Kleine-König
2020-09-24 7:23 ` Qiang Zhao
2020-09-24 7:47 ` Alexandre Belloni
2020-09-24 10:52 ` [PATCH 0/2] rtc: pcf2127: only use watchdog when explicitly available Uwe Kleine-König
2020-09-24 10:52 ` [PATCH 1/2] rtc: pcf2127: move watchdog initialisation to a separate function Uwe Kleine-König
2020-09-27 7:50 ` Bruno Thomsen
2020-09-24 10:52 ` [PATCH 2/2] [RFC] rtc: pcf2127: only use watchdog when explicitly available Uwe Kleine-König
2020-09-27 8:09 ` Bruno Thomsen
2020-09-27 15:54 ` Guenter Roeck
2020-09-28 8:43 ` Uwe Kleine-König
2020-09-28 16:26 ` Guenter Roeck
2020-10-26 7:23 ` [PATCH 0/2] " Qiang Zhao
2020-10-26 20:48 ` Alexandre Belloni
2020-10-26 21:29 ` Guenter Roeck
2020-11-30 9:51 ` Rasmus Villemoes
2020-12-04 9:27 ` Alexandre Belloni
2020-12-11 21:56 ` [PATCH v2 0/3] add reset-source RTC binding, update pcf2127 driver Rasmus Villemoes
2020-12-11 21:56 ` [PATCH v2 1/3] dt-bindings: rtc: add reset-source property Rasmus Villemoes
2020-12-11 22:30 ` Rob Herring
2020-12-11 23:10 ` Rasmus Villemoes
2020-12-17 16:51 ` Rob Herring
2020-12-17 18:12 ` Uwe Kleine-König [this message]
2020-12-17 18:23 ` Rasmus Villemoes
2020-12-17 19:02 ` Rob Herring
2020-12-17 20:28 ` Uwe Kleine-König
2020-12-12 9:25 ` Uwe Kleine-König
2020-12-11 21:56 ` [PATCH v2 2/3] rtc: pcf2127: move watchdog initialisation to a separate function Rasmus Villemoes
2020-12-11 21:56 ` [PATCH v2 3/3] rtc: pcf2127: only use watchdog when explicitly available Rasmus Villemoes
2020-12-18 10:10 ` [PATCH v3 0/2] add reset-source RTC binding, update pcf2127 driver Rasmus Villemoes
2020-12-18 10:10 ` [PATCH v3 1/2] dt-bindings: rtc: add reset-source property Rasmus Villemoes
2020-12-18 21:19 ` Rob Herring
2020-12-18 10:10 ` [PATCH v3 2/2] rtc: pcf2127: only use watchdog when explicitly available Rasmus Villemoes
2020-12-19 0:58 ` [PATCH v3 0/2] add reset-source RTC binding, update pcf2127 driver Alexandre Belloni
2020-09-24 16:59 ` [Patch v2 1/3] dt-bindings: rtc: pcf2127: Add bindings for nxp,pcf2127 Bruno Thomsen
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