From: Guenter Roeck <linux@roeck-us.net>
To: Arnd Bergmann <arnd@kernel.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>
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>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
"linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>
Subject: Re: [PATCH 0/2] add ripple counter dt binding and driver
Date: Mon, 1 Mar 2021 06:21:51 -0800 [thread overview]
Message-ID: <f9f480b1-7b71-ee6d-a018-507b327d8d84@roeck-us.net> (raw)
In-Reply-To: <CAK8P3a0tTQKZ6=55yCQx=60iBt1L6RZzzSvSJMmfKYUkgiWjrQ@mail.gmail.com>
On 3/1/21 1:44 AM, Arnd Bergmann wrote:
> On Mon, Mar 1, 2021 at 9:34 AM Rasmus Villemoes
> <linux@rasmusvillemoes.dk> wrote:
>> On 26/02/2021 20.53, Guenter Roeck wrote:
>>>
>>> Sorry, I am missing something. If the watchdog is controlled by the clock,
>>> it is a consumer of that clock.
>>
>> But that's just it, the watchdog chip is _not_ a consumer of the clock -
>> I don't think I've ever seen a gpio_wdt that is not internally clocked,
>> but even if they exist, that's not the case for this board.
>>
>> What else does "consumer" mean ? And why
>>> not just add optional clock support to the gpio_wdt driver ?
>>
>> Because, the consumer is a piece of electronics sitting _between_ the
>> watchdog chip's reset output and the SOCs reset pin, namely the ripple
>> counter that implements a 64 ms delay from the watchdog fires till the
>> actual reset. (The watchdog's reset is also routed directly to an
>> interrupt; so software gets a 64 ms warning that a hard reset is imminent).
>
> I think it's a question of how you look at what the gpio_wdt device is.
> While physical gpio chip is not a consumer of the clock, I agree with
> Guenter that the conceptual device is: The functionality of the watchdog
> in this case is provided by the combination of the external chip with the
> ripple counter. I think it is therefore appropriate to have the gpio_wdt
> and the driver refer to the clock as part of the watchdog.
>
I agree. All electronics needed for the watchdog to operate is part of the
watchdog, and for me that includes the circuitry that connects it to the
reset pin. The clock is needed for proper watchdog operation, so I would
consider the watchdog to be a consumer.
Guenter
next prev parent reply other threads:[~2021-03-01 14:23 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 14:14 [PATCH 0/2] add ripple counter dt binding and driver Rasmus Villemoes
2021-02-26 14:14 ` [PATCH 1/2] dt-bindings: misc: add binding for generic ripple counter Rasmus Villemoes
2021-03-08 17:21 ` Rob Herring
2021-03-08 20:02 ` Rasmus Villemoes
2021-03-08 21:38 ` Rob Herring
2021-03-09 7:39 ` Rasmus Villemoes
2021-03-09 15:44 ` Rob Herring
2021-02-26 14:14 ` [PATCH 2/2] drivers: misc: add ripple counter driver Rasmus Villemoes
2021-02-28 5:47 ` Chen, Mike Ximing
[not found] ` <CAHp75Vc8S2E0vWFcqK-jO9Nhd-Us_7t-aWNj-7k+fWDcqR1XkQ@mail.gmail.com>
2021-02-28 9:29 ` Andy Shevchenko
2021-02-28 9:33 ` Andy Shevchenko
2021-03-01 8:29 ` Rasmus Villemoes
2021-02-26 14:35 ` [PATCH 0/2] add ripple counter dt binding and driver Arnd Bergmann
2021-02-26 16:35 ` Rasmus Villemoes
2021-02-26 19:53 ` Guenter Roeck
2021-03-01 8:34 ` Rasmus Villemoes
2021-03-01 9:44 ` Arnd Bergmann
2021-03-01 14:21 ` Guenter Roeck [this message]
2021-03-04 22:12 ` [PATCH v2 0/3] add "delay" clock support to gpio_wdt Rasmus Villemoes
2021-03-04 22:12 ` [PATCH v2 1/3] clk: add devm_clk_prepare_enable() helper Rasmus Villemoes
2021-03-09 5:28 ` Guenter Roeck
2022-03-05 2:41 ` Dmitry Torokhov
2021-03-04 22:12 ` [PATCH v2 2/3] dt-bindings: watchdog: add optional "delay" clock to gpio-wdt binding Rasmus Villemoes
2021-03-04 22:12 ` [PATCH v2 3/3] watchdog: gpio_wdt: implement support for optional "delay" clock Rasmus Villemoes
2021-03-09 5:51 ` [PATCH v2 0/3] add "delay" clock support to gpio_wdt Guenter Roeck
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