linux-kernel - Re: [PATCH 0/8] watchdog: Add support for keepalives triggered by infrastructure

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Message-ID: <55C0D3C2.6020709@roeck-us.net>
Date:	Tue, 04 Aug 2015 08:01:22 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
CC:	linux-watchdog@...r.kernel.org, Wim Van Sebroeck <wim@...ana.be>,
	linux-kernel@...r.kernel.org,
	Timo Kokkonen <timo.kokkonen@...code.fi>,
	linux-doc@...r.kernel.org, Jonathan Corbet <corbet@....net>
Subject: Re: [PATCH 0/8] watchdog: Add support for keepalives triggered by
 infrastructure

Hi Uwe,

On 08/04/2015 04:24 AM, Uwe Kleine-König wrote:
> Hello Guenter,
>
> On Mon, Aug 03, 2015 at 07:13:26PM -0700, Guenter Roeck wrote:
>> This patch set does not solve all limitations of the watchdog subsystem.
>> Specifically, it does not add support for the following features.
>>
>> - It is desirable to be able to specify a maximum early timeout,
>>    from booting the system to opening the watchdog device.
>> - Some watchdogs may require a minimum period of time between
>>    heartbeats. Examples are DA9062 and possibly AT91SAM9x.
>
> Other things that come to my mind:
>   - move handling of nowayout into the core
>   - some drivers use a reboot notifier. Not sure what they are intended
>     to do there. For i.MX2x it triggers a reboot; for gpio-wdt it tries
>     to stop the watchdog.
>
Be careful - those are different functions. The imx2 driver installs
a _restart_ handler, which indeed is supposed to restart the system.
The gpio wdt driver installs a _reboot_ notifier, which is supposed to
stop the watchdog. Other drivers install a shutdown callback in the
platform driver structure to do the same; not really sure what is better.

> Of course this doesn't mean this should addressed here. I like the
> series in general.
>

The list wasn't supposed to be exhaustive. Otherwise adding "support devm"
should have been there as well. I even have a patch hanging around somewhere
to do that. Guess I should have said something like "does not solve all
timeout related limitations ...".

Thanks,
Guenter

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