From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B808DC678D4 for ; Thu, 2 Mar 2023 17:06:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229523AbjCBRGW (ORCPT ); Thu, 2 Mar 2023 12:06:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45448 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229482AbjCBRGV (ORCPT ); Thu, 2 Mar 2023 12:06:21 -0500 Received: from relay2-d.mail.gandi.net (relay2-d.mail.gandi.net [217.70.183.194]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D0F63E638 for ; Thu, 2 Mar 2023 09:06:19 -0800 (PST) Received: (Authenticated sender: kory.maincent@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id D46354000C; Thu, 2 Mar 2023 17:06:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1677776778; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7OxCSAS5AYzV8pl7UsWlzTATitYRoOqLZklO4rA7x6A=; b=nwY7OBbcIBFNr46ZOhvGSpnqvd8/OYO52uPZ0V2dfcUqaJcYwcoNpkFAQXkU9C2gNSsl1A GgB1HUBq9SAeMObs+BhSxaIjYkEfdaym4fkylCbJOSHhzSGTEFtQhAQoftvme+9GDIHKMM 6MyKfZ88maYXKGAST1mipye23M7T+WEUE5cVjoN7fcLO4iOMH/ZlihvQwtxCzFO7JCEh2i jFKjwTg0Cl1XyQCIWep0v/yv+lBFXYxvIMSVoQirZ7wNTFEJV5Aob5e9Hh58xtsWJIE3N3 4ocGnBbOyOeVbjVVENoiHLryLsqPvRhjDFznqhYOGDs4DK5o695IHbMBbQHkJA== Date: Thu, 2 Mar 2023 18:06:16 +0100 From: =?UTF-8?B?S8O2cnk=?= Maincent To: Jakub Kicinski Cc: "Russell King (Oracle)" , Richard Cochran , andrew@lunn.ch, davem@davemloft.net, f.fainelli@gmail.com, hkallweit1@gmail.com, netdev@vger.kernel.org, Thomas Petazzoni , Maxime Chevallier Subject: Re: [PATCH RFC net-next] net: phy: add Marvell PHY PTP support [multicast/DSA issues] Message-ID: <20230302180616.7bcfc1ef@kmaincent-XPS-13-7390> In-Reply-To: <20230302084932.4e242f71@kernel.org> References: <20230228141630.64d5ef63@kmaincent-XPS-13-7390> <20230228142648.408f26c4@kernel.org> <20230228145911.2df60a9f@kernel.org> <20230301170408.0cc0519d@kmaincent-XPS-13-7390> <20230302084932.4e242f71@kernel.org> Organization: bootlin X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, 2 Mar 2023 08:49:32 -0800 Jakub Kicinski wrote: > On Thu, 2 Mar 2023 11:49:26 +0000 Russell King (Oracle) wrote: > > (In essence, because of all the noise when trying the Marvell PHY with > > ptp4l, I came to the conlusion that NTP was a far better solution to > > time synchronisation between machines than PTP would ever be due to > > the nose induced by MDIO access. However, I should also state that I > > basically gave up with PTP in the end because hardware support is > > overall poor, and NTP just works - and I'd still have to run NTP for > > the machines that have no PTP capabilities. PTP probably only makes > > sense if one has a nice expensive grand master PTP clock on ones > > network, and all the machines one wants to synchronise have decent > > PTP implementations.) =20 >=20 > Don't wanna waste too much of your time with the questions since > I haven't done much research but - wouldn't MAC timestamp be a better > choice more often (as long as it's a real, to-spec PTP stamp)?=20 > Are we picking PHY for historical reasons? >=20 > Not that flipping the default would address the problem of regressing > some setups.. I have measured it with the Marvell PHY and MACB MAC but it is the contrary= on my side: https://lkml.kernel.org/netdev/20230302113752.057a3213@kmaincent-XPS-13-739= 0/ Also PHY default seems more logical as it is nearer to the physical link, b= ut still I am interesting by the answer as I am not a PTP expert. Is really PTP MAC often more precise than PTP PHY? Regards, K=C3=B6ry