From: "Daniel Glöckner" <dg@emlix•com>
To: Richard Cochran <richardcochran@gmail•com>
Cc: netdev@vger•kernel.org
Subject: Re: PTP_PEROUT_REQUEST and clock stepping
Date: Thu, 11 Sep 2014 11:52:45 +0200 [thread overview]
Message-ID: <20140911095245.GA5823@emlix.com> (raw)
In-Reply-To: <20140910172619.GB5944@localhost.localdomain>
On Wed, Sep 10, 2014 at 07:26:20PM +0200, Richard Cochran wrote:
> On Wed, Sep 10, 2014 at 06:16:37PM +0200, Daniel Glöckner wrote:
> > I was wondering how periodic output is supposed to behave if the clock
> > is stepped from a time after ptp_perout_request.start to a time before
> > ptp_perout_request.start.
>
> I would say the result is undefined.
>
> User space should first stop the periodic output, then reprogram the
> clock, then restart the periodic output. Anything else makes no sense
> at all.
But then the PTP demon has to be responsible for configuring the periodic
outputs as well.
IMHO there is no use for a .start value > .period. It is good for defining
the phase of the periodic output but is just annoying if you want to have
the periodic output running all the time. Only a small fraction of people
using periodic outputs will want to schedule the start of the signal at
a specific time in the future and only a fraction of those will use a
.period value that is so small that they can't use a timer to configure
the periodic output within .period/2 before the desired start time.
Best regards,
Daniel
--
Dipl.-Math. Daniel Glöckner, emlix GmbH, http://www.emlix.com
Fon +49 551 30664-0, Fax +49 551 30664-11,
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emlix - your embedded linux partner
next prev parent reply other threads:[~2014-09-11 9:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-10 16:16 PTP_PEROUT_REQUEST and clock stepping Daniel Glöckner
2014-09-10 17:26 ` Richard Cochran
2014-09-11 9:52 ` Daniel Glöckner [this message]
2014-09-12 6:17 ` Christian Riesch
2014-09-12 6:24 ` Christian Riesch
2014-09-12 6:33 ` Richard Cochran
2014-09-12 11:40 ` Daniel Glöckner
2014-09-12 14:40 ` Richard Cochran
2014-09-12 15:19 ` Daniel Glöckner
2014-09-13 9:19 ` Richard Cochran
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