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Date: Fri, 19 Oct 2007 10:14:54 +1000
From: Paul Mackerras <paulus@samba.org>
To: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Subject: Re: [PATCH v2 3/4] Implement clockevents driver for powerpc
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Cc: linuxppc-dev@ozlabs.org, Thomas Gleixner <tglx@linutronix.de>,
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Sergei Shtylyov writes:

> > What problem do you see arising from this?
> 
>     Timers firing too early.

Only if the minimum interrupt latency is less than 1 decrementer
tick.  That seems pretty unlikely to me unless you have a very slow
timebase frequency.

In fact what we should program the decrementer to is:

	timeout - (is_booke? 0: 1) - min_interrupt_latency

I was assuming that min_interrupt_latency (measured in timebase ticks)
would be at least 1, but apparently some systems can have a timebase
frequency as low as 1kHz, so we'll have to have an ifdef or something.

Paul.