From: Wim Van Sebroeck <wim@iguana.be>
To: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: Linux kernel <linux-kernel@vger.kernel.org>, linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] fix book E watchdog to take WDIOC_SETTIMEOUT arg in seconds
Date: Thu, 27 Aug 2009 22:27:09 +0200 [thread overview]
Message-ID: <20090827202709.GK29382@infomag.iguana.be> (raw)
In-Reply-To: <20090827120841.GA25303@zod.rchland.ibm.com>
Hi Josh,
> >Now we only need someone that can look at the CONFIG_4xx cases still :-)
>
> It seems the FSL watchdog is much more flexible than the one found in 4xx
> cores. On 4xx, you basically have 4 static choices that represent specific
> times determined by the clock frequency. I'm concerned that the lack of
> granularity here will result in less than desirable behavior.
>
> For example, with a 400MHz clock you would get choices of roughly:
>
> 5.2 ms
> 83.9 ms
> 1.34 s
> 21.47 s
>
> Personally, I consider the first two options basically unusable. Considering
> the second two, if a user were to say "Set the timeout for 2 seconds" they
> would then get a timeout of 21 seconds with the framework Chris' patch has
> set up. That doesn't really seem to be ideal to me.
Hmm, my opinion: in that case we should use a timer that triggers the watchdog until userspaces times out (like we do for other watchdogs allready). Maybe we should split this driver. I have the same issue with the Freescale i.mx driver that is under review also.
Kind regards,
Wim.
prev parent reply other threads:[~2009-08-27 20:27 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-12 18:02 [PATCH] fix book E watchdog to take WDIOC_SETTIMEOUT arg in seconds Chris Friesen
2009-08-27 11:14 ` Wim Van Sebroeck
2009-08-27 12:08 ` Josh Boyer
2009-08-27 20:27 ` Wim Van Sebroeck [this message]
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