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Re: clockevent driver as source for pretimout watchdog interrupt

From Thomas Gleixner <tglx@linutronix.de>
Newsgroups linux.kernel
Subject Re: clockevent driver as source for pretimout watchdog interrupt
Date 2016-04-21 10:50 +0200
Message-ID <rqitc-6j1-21@gated-at.bofh.it> (permalink)
References <rqitc-6j1-23@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Thu, 21 Apr 2016, fixed-term.Oleksij.Rempel wrote:
> i'm doing research on proper implementation for watchdog pretimout
> interrupt for devices which do not provide this functionality.
> 
> Some watchdog controllers like Freescale iMX6 can generate an interrupt
> for some configured time before watchdog will reset the system.
> Suddenly most watchdog controllers don't have this functionality.
> 
> My idea is to reuse some count down (one shot?) timer:
> - configure it to generate an interrupt for a time less then watchdog
> deadline.
> - reset it each time we get a ping, before an interrupt is generated.
> - interrupt should executed one of governors from pretimout patchset,
> see the link:
> https://www.mail-archive.com/linux-watchdog@vger.kernel.org/msg02394.html
> 
> I assume clocksource framework is kind of suitable for this purpose? Is
> it correct assumption?
> Any other ideas? Suggestions?

What's wrong with simply using a hrtimer for this? The extra clockevent is not
buying you anything AFAICT.

Thanks,

	tglx

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Re: clockevent driver as source for pretimout watchdog interrupt Thomas Gleixner <tglx@linutronix.de> - 2016-04-21 10:50 +0200

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