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 C54FC2918 for ; Thu, 11 May 2023 20:55:54 +0000 (UTC) Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A17B7AA7 for ; Thu, 11 May 2023 13:55:47 -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=JJiaQU12yzpcHDmDZXidl0vSf/eoI8EDoa48hrwnJpA=; b=0A0R9AMnyKI+aoxnbaPS6HV5Gj 4zWqLkYl+7b7lURoSkIzeQ8c4au3kdX2cs6XmcsPN4ok+uFFANs6UngvkDSXUmRuKxgQ61iHvyVrQ 814Bvi/RbO3a4izu0U+MWkIcBOt0DQZa67xvtdUY6tg40GZhYnP5umQ0cATHaHbLSUTV66FcpR9sL HcqRUM0vn+Id9r1w+Wxvi7bzOGllwxUwAFB7dxUavlImXyl658KVAg+t/5mPc/1ItniRTEz9Qw2Ny sl/6sl8hi5gSUqZEQaMOHD9PDvWkuNFUfzbb0ZtrcE2wV/bFrUZanj8V6qigPss5SQ/x9j2dzJO+C dstU7MNA==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:38902) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1pxDKA-0007Fi-Gx; Thu, 11 May 2023 21:55:42 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1pxDK7-0004Ln-Ul; Thu, 11 May 2023 21:55:39 +0100 Date: Thu, 11 May 2023 21:55:39 +0100 From: "Russell King (Oracle)" To: Andrew Lunn Cc: Vladimir Oltean , Jakub Kicinski , =?iso-8859-1?Q?K=F6ry?= Maincent , netdev@vger.kernel.org, glipus@gmail.com, maxime.chevallier@bootlin.com, vadim.fedorenko@linux.dev, richardcochran@gmail.com, 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: <20230406173308.401924-1-kory.maincent@bootlin.com> <20230406173308.401924-3-kory.maincent@bootlin.com> <20230406184646.0c7c2ab1@kernel.org> <20230511203646.ihljeknxni77uu5j@skbuf> <54e14000-3fd7-47fa-aec3-ffc2bab2e991@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: <54e14000-3fd7-47fa-aec3-ffc2bab2e991@lunn.ch> Sender: Russell King (Oracle) X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Thu, May 11, 2023 at 10:50:30PM +0200, Andrew Lunn wrote: > On Thu, May 11, 2023 at 11:36:46PM +0300, Vladimir Oltean wrote: > > On Thu, Apr 06, 2023 at 06:46:46PM -0700, Jakub Kicinski wrote: > > > > +/* Hardware layer of the SO_TIMESTAMPING provider */ > > > > +enum timestamping_layer { > > > > + SOF_MAC_TIMESTAMPING = (1<<0), > > > > + SOF_PHY_TIMESTAMPING = (1<<1), > > > > > > We need a value for DMA timestamps here. > > > > What's a DMA timestamp, technically? Is it a snapshot of the PHC's time > > domain, just not at the MII pins? > > I also wounder if there is one definition of DMA timestampting, or > multiple. It could simply be that the time stamp is in the DMA > descriptor, Surely that is equivalent to MAC timestamping? Whether the MAC places it in a DMA descriptor, or whether it places it in some auxiliary information along with the packet is surely irrelevant, because the MAC has to have the timestamp available to it in some manner. Where it ends up is just a function of implementation surely? I'm just wondering what this would mean for mvpp2, where the timestamps are in the descriptors. If we have a "DMA timestamp" is that a "DMA timestamp" or a "MAC timestamp"? The timestamp comes from the MAC in this case. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!