From mboxrd@z Thu Jan  1 00:00:00 1970
From: Richard Cochran <richardcochran@gmail.com>
Subject: Re: PTP_PEROUT_REQUEST and clock stepping
Date: Fri, 12 Sep 2014 16:40:25 +0200
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Cc: Christian Riesch <christian.riesch@omicron.at>,
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To: Daniel =?iso-8859-1?Q?Gl=F6ckner?= <dg@emlix.com>
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On Fri, Sep 12, 2014 at 01:40:32PM +0200, Daniel Gl=F6ckner wrote:
> You mean the hardware that you know of that currently exists.

Yes, that is the hardware we support. I am sorry that I don't know how
to support mythical hardware.
=20
> I just think it is wrong to place the burden of stopping and starting
> the periodic output on the PTP demon.

I think it is the right place.

> The kernel knows when clock_adjtime
> and clock_settime are called and it also knows which periodic outputs
> are enabled and how they are configured. We just have to decide on th=
e
> correct behavior (respect .start vs. ignore .start once running) to b=
e
> implemented.

The only reasonable actions for kernel would be to either stop all
periodic outputs, or to just do nothing.
=20
> Taking the Intel i210 as an example, the third option (doing nothing)
> would lead to the following behavior:
>=20
>  - If the clock is stepped back, the periodic output stops until the
>    clock reaches the point when it was adjusted.
>=20
>  - If the clock is stepped forward, the periodic output oscillates at
>    62,5 MHz to catch up.

That is a good example of "the results are undefined".

So, how would you reprogram the i210 to keep the period output
continuous?

Thanks,
Richard