Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751946Ab3IJUOw (ORCPT ); Tue, 10 Sep 2013 16:14:52 -0400 Received: from catbert.rellim.com ([204.17.205.1]:49977 "EHLO catbert.rellim.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751485Ab3IJUOv (ORCPT ); Tue, 10 Sep 2013 16:14:51 -0400 X-Greylist: delayed 690 seconds by postgrey-1.27 at vger.kernel.org; Tue, 10 Sep 2013 16:14:51 EDT X-DKIM: OpenDKIM Filter v2.6.7 catbert.rellim.com r8AK2ZG9028308 Date: Tue, 10 Sep 2013 13:02:34 -0700 From: "Gary E. Miller" To: Rodolfo Giometti Cc: Paul Chavent , linux-usb@vger.kernel.org, gregkh@linuxfoundation.org, jhovold@gmail.com, fschaefer.oss@googlemail.com, jslaby@suse.cz, max@suse.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/5] Enable PPS reporting for USB serial devices Message-ID: <20130910130234.5106a5bc.gem@rellim.com> In-Reply-To: <20130910073105.GB5030@enneenne.com> References: <1378742480-2146-1-git-send-email-paul.chavent@onera.fr> <20130910073105.GB5030@enneenne.com> Organization: Rellim X-Mailer: Claws Mail 3.9.0 (GTK+ 2.24.17; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/J/GK1Vgcy9PykKEOOXx7.VW"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2041 Lines: 52 --Sig_/J/GK1Vgcy9PykKEOOXx7.VW Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Yo Rodolfo! On Tue, 10 Sep 2013 09:31:05 +0200 Rodolfo Giometti wrote: > I have nothing against with this solution but consider that reporting > a PPS signal through USB bus may add unknown delays that may vanish > clock stability... as far as I know you should not use USB serial port > with PPS. Have you some statistics about clock stability in a real > implementation? gpsd project has been using PPS over USB 1.1 for over a year. Typical accuracy and repeatability in the range of +/- 1 milliSec. This is much better than you can get using simple ntp over gigabit ethernet to an adjacent stratum 1 server. Sure PPS over a local UART is 10 to 100 times better, but often PPS over USB is your best second choice. As serial ports become extinct it may become your best choice. RGDS GARY --------------------------------------------------------------------------- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701 gem@rellim.com Tel:+1(541)382-8588 --Sig_/J/GK1Vgcy9PykKEOOXx7.VW Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.20 (GNU/Linux) iQEcBAEBAgAGBQJSL3raAAoJEA0O2UlB0XnYih8IAISSauU3exhI0UtPLX/0IHPF uX+c7ZboqXxbZ5Fid7zS+7mf3BVzkpmIeQOYQ23VP0mAiZ19BjvZAvqR199uq1mR YoCuiypWSfZyYv3UbgMdhSC6SQOuFNartZzswnVA0YvYImsOI1Qlw1/3/Sd5SrCt 6D/+4MaJEDe8yX/3aJ06a0ro9Som7DLJEXV3WRlKrSni6rwtEbIva0uhvIjgbllw 123MCtpYDuT2HQpLiBWONeO7ma5uvf+5DsYjE2mnr9ozMd/8LXtZF0Nuzcp9B3ZP HMvU3NOebnN/WS6ackpsmBFsdMgZiTfcJccN1ThdNRq6myk6vGl6sCC9qcXSGq4= =CJgr -----END PGP SIGNATURE----- --Sig_/J/GK1Vgcy9PykKEOOXx7.VW-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/