linux-kernel - Re: [PATCH 2/3] ptp: add a software clock based on clock_monotonic

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Message-ID: <20110306132834.GA11790@riccoc20.at.omicron.at>
Date:	Sun, 6 Mar 2011 14:28:36 +0100
From:	Richard Cochran <richardcochran@...il.com>
To:	john stultz <johnstul@...ibm.com>
Cc:	Torben Hohn <torbenh@....de>, linux-kernel@...r.kernel.org,
	richard.cochran@...cron.at, tglx@...utronix.de
Subject: Re: [PATCH 2/3] ptp: add a software clock based on
 clock_monotonic_raw

On Sat, Mar 05, 2011 at 12:08:07PM -0800, john stultz wrote:
> On Fri, 2011-03-04 at 07:46 +0100, Richard Cochran wrote:
> > I do think a software only PHC will make it easier for people to get
> > started with the new interface. I have been carrying along such a
> > patch privately for my own testing.
> 
> Consistency is but a hobgoblin... :)
> 
> But seriously, do forgive me if I misunderstood your earlier patches
> with this respect. I thought it was just exporting CLOCK_REALTIME
> directly through a new interface/clockid (which would be duplicative).

You are right, I was doing that, but the purpose was for testing.

I am not sure where Torben is going with his idea. In order to figure
out meaningful clock adjustments, you need the clock's timestamps on
the PTP packet tx/rx events. Implementing an internal clock correction
with no connection to the network stack might still be interesting,
but I think having the timestamps is much more useful.

Let's wait and see what Torben says once he come back from travel.

Thanks,

Richard
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