From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Alessandro Zummo <a.zummo@towertech.it>,
Rob Herring <robh+dt@kernel.org>,
linux-rtc@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] dt-bindings: rtc: pcf2127: update bindings
Date: Wed, 27 Jan 2021 14:18:21 +0100 [thread overview]
Message-ID: <20210127131821.GH1196852@piout.net> (raw)
In-Reply-To: <0a8fd7f3-58c1-9e20-bcfa-9872b3dc3550@prevas.dk>
On 27/01/2021 14:07:59+0100, Rasmus Villemoes wrote:
> On 26/01/2021 23.48, Alexandre Belloni wrote:
> > On 21/12/2020 22:17:54+0100, Rasmus Villemoes wrote:
> >> On 19/12/2020 02.34, Alexandre Belloni wrote:
> >>> pcf2127, pcf2129 and pca2129 support start-year and reset-source.
> >>>
> >>
> >> No, the 2129 variant doesn't even have a reset output pin. Not sure if
> >> there's any way to reflect that, and it probably doesn't matter, since
> >> nobody's going to add the reset-source property to a 2129 node. But the
> >> commit message is a bit misleading.
> >>
> >
> > Actually no, the INT pin can be used as a reset, the pcf/pca2129
> > can be used as a watchdog and so it may need the reset-source property.
>
> Unless I'm missing something, that would require some rather creative
> extra circuitry: The interrupt pin is kept low until the appropriate bit
> in the rtc is cleared, so if that is routed directly to a reset pin on
> the SOC, the SOC would be kept in reset indefinitely.
>
You mean inverting the level of INT? I don't think this is creative or
complicated...
And anyway, INT# is active low, like RST# so if the SoC has an RST#
input, this should just work.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2021-01-27 13:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-19 1:34 [PATCH] dt-bindings: rtc: pcf2127: update bindings Alexandre Belloni
2020-12-21 21:17 ` Rasmus Villemoes
2020-12-21 21:39 ` Alexandre Belloni
2021-01-26 22:48 ` Alexandre Belloni
2021-01-27 13:07 ` Rasmus Villemoes
2021-01-27 13:18 ` Alexandre Belloni [this message]
2021-01-27 13:49 ` Rasmus Villemoes
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