From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1E95A28E7 for ; Thu, 7 Sep 2023 16:01:06 +0000 (UTC) Received: from pandora.armlinux.org.uk (unknown [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 44B405261 for ; Thu, 7 Sep 2023 09:00:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=iW9qexjhy8+LyUL+K3aytg7/qTwPeKlLpqIkH3ZXji0=; b=jGG0c1D10CSnKpz1tY7DxglbkW 7aRSvKvH8L3bTau3Dm3hy94mbC7jpzBPi66IOog4PXyZ9qIf9OVm4Mpi1AzT+C8nxTrrDygbHzk4G htPbFECv05h8bZMPoLqH2imjz0FODQ2azZHsn7cDyH6ouDeb85bxtb6tabZivfuRdppvlF1qTdmET ezb70l1qY/TC8UOqq1TdB26+hG5y3F2B+0LdyZEqmOWH7CFil6FHD7YI4EFTaIiGWnL4QnTcizBSl 3LYFQP+gU33vypEfoI24Uzv1vjhebAn3tm/TujXEIoXeb7U8Z970QRfGPJyhnfG8rtjkOrsHeFtHo Kut3IM/Q==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:54310) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1qeBKW-0001qD-2B; Thu, 07 Sep 2023 10:29:40 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1qeBKW-0005iw-1R; Thu, 07 Sep 2023 10:29:40 +0100 Date: Thu, 7 Sep 2023 10:29:39 +0100 From: "Russell King (Oracle)" To: Andrew Lunn Cc: Jakub Kicinski , Richard Cochran , =?iso-8859-1?Q?K=F6ry?= Maincent , Vladimir Oltean , netdev@vger.kernel.org, glipus@gmail.com, maxime.chevallier@bootlin.com, vadim.fedorenko@linux.dev, gerhard@engleder-embedded.com, thomas.petazzoni@bootlin.com, krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org Subject: Re: [PATCH net-next RFC v4 2/5] net: Expose available time stamping layers to user space. Message-ID: References: <20230511161625.2e3f0161@kernel.org> <20230512102911.qnosuqnzwbmlupg6@skbuf> <20230512103852.64fd608b@kernel.org> <20230517121925.518473aa@kernel.org> <2f89e35e-b1c9-4e08-9f60-73a96cc6e51a@lunn.ch> <20230517130706.3432203b@kernel.org> <20230904172245.1fa149fd@kmaincent-XPS-13-7390> <20230905114717.4a166f79@kernel.org> <8fd9f2bc-f8a2-4290-8e52-17a39175b3d7@lunn.ch> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8fd9f2bc-f8a2-4290-8e52-17a39175b3d7@lunn.ch> Sender: Russell King (Oracle) X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED,RDNS_NONE, SPF_HELO_NONE,SPF_NONE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Tue, Sep 05, 2023 at 10:29:51PM +0200, Andrew Lunn wrote: > > Maybe we should try to enumerate the use cases, I don't remember now > > but I think the concern was that there may be multiple PHYs? > > You often see a Marvell 10G PHY between a MAC and an SFP cage. You can > then get a copper SFP module which has a PHY in it. > > So: > > "Linux" NIC: [DMA MAC][PHY][PHY] Let's be clear - one of the reasons that this whole topic was triggered was because of mvpp2 plus Marvell 1G PHYs. mvpp2 has a good PTP implementation, where as Marvell 1G PHYs are not quite as good. With the code as it stood, merely adding PTP support to Marvell PHYs would result in setups that use a Marvell 1G PHY with mvpp2 to break - some PTP API calls would end up going to one PTP implementation while other PTP API calls end up going to the other. Once this gets solved properly, then I can think about sending the patches that add support for PTP in Marvell 1G PHYs, and then we will have the situation where we have a MAC and a PHY on the *same* network interface that are PTP capable. People have been asking me about the Marvell PHY PTP patches - and I have had to tell them that they can't be merged because of the PTP API crazyness. So... it would be entirely possible, if PTP were to be implemented for the Marvell 10G PHYs, that there would be _three_ points with a SFP module to do PTP, although it probably does not make much sense to attempt to do so on the SFP PHY. In any case, before we get to that point, we first need to work out how to support multiple ethernet PHYs on one MAC. Even with that solved, the situation you describe above is likely to be problematical. PHYs that connect to SFPs generally only support fibre interface modes and not SGMII on that port which limits the usefulness of copper SFPs - they won't be able to do 10M / 100M unless they're one of those PHYs that does rate adaption which seem fairly rare at the moment. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!