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Date: Fri, 18 Jul 2014 00:21:47 +0200
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai] [PATCH] AT91: SAMA5D3: Adapt Ipipe for AIC5
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To: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Thomas Petazzoni <thomas@free-electrons.com>, Nicolas Ferre <nicolas.ferre@atmel.com>, Boris Brezillon <boris@free-electrons.com>, Alexandre Belloni <alexandre.belloni@free-electrons.com>, xenomai@xenomai.org

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On 07/17/2014 01:59 PM, Maxime Ripard wrote:
> On Thu, Jul 17, 2014 at 12:54:10PM +0200, Gilles Chanteperdrix
> wrote:
>>> Which brings an extra question about this. Is the timer 
>>> calibration supposed to get a minimum latency to 0 (meaning
>>> that with a properly calibrated timer, we would only get
>>> positive latencies), or that the average latency should be
>>> around 0 (which would mean that negative latencies would
>>> actually be frequent, but would break the clock_nanosleep
>>> documented behaviour).
>>> 
>>> I'm actually seeing the former, but trying the latter only
>>> brings us quite close to having the calibration disabled
>>> entirely.
>> 
>> The calibration is left entirely to the user, so, you choose what
>> is best for your application. But indeed, if your application
>> relies on clock_nanosleep documented behaviour (should never
>> wake-up early except in case of signal), you want to set
>> /proc/xenomai/latency value to the minimum value measured by the
>> latency test, minus a safety margin.
> 
> Ok, thanks!
> 
> I guess you can add my Tested-by tag to your patch, if that makes
> any sense for Xenomai.

We do not consistently use the signed-off mechanism, but I have added
your Tested-by anyway, thanks.

- -- 
                                                                Gilles.
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