From mboxrd@z Thu Jan  1 00:00:00 1970
From: Timur Tabi <timur@codeaurora.org>
Subject: Re: [PATCH v10 5/5] Watchdog: ARM SBSA Generic Watchdog half timeout
 panic support
Date: Wed, 3 Feb 2016 12:08:59 -0600
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To: Fu Wei <fu.wei@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>, =?UTF-8?Q?Pawe=c5=82_Moll?= <pawel.moll@arm.com>, Mark Rutland <mark.rutland@arm.com>, Ian Campbell <ijc+devicetree@hellion.org.uk>, Kumar Gala <galak@codeaurora.org>, Wim Van Sebroeck <wim@iguana.be>, Guenter Roeck <linux@roeck-us.net>, Jon Corbet <corbet@lwn.net>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>, LKML <linux-kernel@vger.kernel.org>, linux-watchdog@vger.kernel.org, linux-doc@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Linaro ACPI Mailman List <linaro-acpi@lists.linaro.org>, rruigrok@codeaurora.org, "Abdulhamid, Harb" <harba@codeaurora.org>, Christopher Covington <cov@codeaurora.org>, Dave Young <dyoung@redhat.com>, Pratyush Anand <panand@redhat.com>, G Gregory <graeme.gregory@linaro.org>, Al
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Fu Wei wrote:
> Actually I am taking your suggestion to avoid touching WCV in
> interrupt routine.
> So even we have pre-timeout support , it is useless for this
> panic-on-half-timeout feature,
> because pre-timeout  == timeout / 2 (always).
>
> So maybe I misunderstand your suggestion,
> could you let me know : why we want pre-timeout here?

Maybe I'm confused.

For pre-timeout, I think the SBSA watchdog driver should support only 
half-timeout.  That is, the user cannot configure the length of the 
pre-timeout with this driver.  He can only enable it, and it is 
automatically set to 1/2 timeout.

So when pre-timeout occurs, the interrupt handler calls panic() or 
whatever it's supposed to do.

So "pre-timeout  == timeout / 2 (always)" is exactly what we want.