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Subject: Re: [PATCH 0/2] add ripple counter dt binding and driver
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>,
        DTML <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        linux-clk <linux-clk@vger.kernel.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        "linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>
References: <20210226141411.2517368-1-linux@rasmusvillemoes.dk>
 <CAK8P3a2=nZ3bbeguXjbFrhz0nWeUOcLM7mRudhPDrcb+jZ4VvQ@mail.gmail.com>
From:   Rasmus Villemoes <linux@rasmusvillemoes.dk>
Message-ID: <e5fd7ce3-3ba6-e5de-1cbc-fa31bd46942c@rasmusvillemoes.dk>
Date:   Fri, 26 Feb 2021 17:35:19 +0100
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On 26/02/2021 15.35, Arnd Bergmann wrote:
> On Fri, Feb 26, 2021 at 3:14 PM Rasmus Villemoes
> <linux@rasmusvillemoes.dk> wrote:
> 
>>
>> So I'm thinking that the proper way to handle this is to be able to
>> represent that ripple counter as a clock consumer in DT and have a
>> driver do the clk_prepare_enable(), even if that driver doesn't and
>> can't do anything else. But I'm certainly open to other suggestions.
> 
> How about adding support for the optional clock to the gpio_wdt driver,
> would that work?

I think it would _work_ (all I need is some piece of code doing the
clock_prepare_enable(), and until now we've just stashed that in some
otherwise unrelated out-of-tree driver, but we're trying to get rid of
that one), but the watchdog chip isn't really the consumer of the clock
signal, so in-so-far as DT is supposed to describe the hardware, I don't
think it's appropriate.

OTOH, one could argue that the watchdog chip and the ripple counter
together constitute the watchdog circuit.

Cc += watchdog maintainers. Context: I have a gpio-wdt which can
unfortunately effectively be disabled by disabling a clock output, and
that happens automatically unless the clock has a consumer in DT. But
the actual consumer is not the gpio-wdt.
Please see
https://lore.kernel.org/lkml/20210226141411.2517368-1-linux@rasmusvillemoes.dk/
for the original thread.

Rasmus