From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel =?iso-8859-1?Q?Gl=F6ckner?= Subject: Re: PTP_PEROUT_REQUEST and clock stepping Date: Thu, 11 Sep 2014 11:52:45 +0200 Message-ID: <20140911095245.GA5823@emlix.com> References: <54107965.6040007@emlix.com> <20140910172619.GB5944@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org To: Richard Cochran Return-path: Received: from mx1.emlix.com ([88.198.240.195]:60151 "EHLO mx1.emlix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752908AbaIKJws (ORCPT ); Thu, 11 Sep 2014 05:52:48 -0400 Content-Disposition: inline In-Reply-To: <20140910172619.GB5944@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Sep 10, 2014 at 07:26:20PM +0200, Richard Cochran wrote: > On Wed, Sep 10, 2014 at 06:16:37PM +0200, Daniel Gl=F6ckner wrote: > > I was wondering how periodic output is supposed to behave if the cl= ock > > is stepped from a time after ptp_perout_request.start to a time bef= ore > > ptp_perout_request.start. >=20 > I would say the result is undefined. >=20 > 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 period= ic outputs as well. IMHO there is no use for a .start value > .period. It is good for defin= ing the phase of the periodic output but is just annoying if you want to ha= ve the periodic output running all the time. Only a small fraction of peop= le 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 =2Eperiod value that is so small that they can't use a timer to configu= re the periodic output within .period/2 before the desired start time. Best regards, Daniel --=20 Dipl.-Math. Daniel Gl=F6ckner, emlix GmbH, http://www.emlix.com =46on +49 551 30664-0, Fax +49 551 30664-11, Bertha-von-Suttner-Stra=DFe 9, 37085 G=F6ttingen, Germany Sitz der Gesellschaft: G=F6ttingen, Amtsgericht G=F6ttingen HR B 3160 Gesch=E4ftsf=FChrung: Dr. Uwe Kracke, Ust-IdNr.: DE 205 198 055 emlix - your embedded linux partner