linux-kernel - Re: [v2,1/4] watchdog: at91sam9

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Message-ID: <20131002204217.GA14148@roeck-us.net>
Date:	Wed, 2 Oct 2013 13:42:17 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	boris brezillon <b.brezillon@...rkiz.com>
Cc:	Wim Van Sebroeck <wim@...ana.be>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
	Ludovic Desroches <ludovic.desroches@...el.com>,
	Yang Wenyou <Wenyou.Yang@...el.com>,
	linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [v2,1/4] watchdog: at91sam9_wdt: better watchdog support

On Wed, Oct 02, 2013 at 09:53:54PM +0200, boris brezillon wrote:
[ ... ]
> >>>>+
> >>>>+	if (!wdt->heartbeat) {
> >>>>+		dev_err(wdt->wdd.parent,
> >>>>+			": sorry, linux timer (%i Hz) cannot handle watchdog timeout (%i ms)\n",
> >>>>+			HZ, ticks_to_ms(value));
> >>>>+		return -EINVAL;
> >>>Isn't that a bit rude ? Why not set it to the minimum ?
> 
> I might have misunderstood your point.
> What is a bit rude ?
>  - the fact that the minimum heartbeat timeout has to be at less or
> equal to one-forth of
>    max heartbeat timeout
>  - the fact that heartbeat expressed in ticks has to be more than 0
>  - something else

That you don't auto-correct the heatbeat to the minimum but return -EINVAL instead.
I prefer to be user-friendly, which in this case would be to accept and handle
the <min, max> timeout values provided to the infrastructure and handle any
deviations / limitaions internally.

Or, in other words, I don't like it if the user ends up having to guess
valid parameter ranges.

Thanks,
Guenter
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