Re: clockevent driver as source for pretimout watchdog interrupt

Re: clockevent driver as source for pretimout watchdog interrupt

[Thomas Gleixner]

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