From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (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 92D1FAD4B; Wed, 22 Jan 2025 19:25:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737573951; cv=none; b=Qhj0x54gjNCUjsGq3z/L0CQhHeh5PbAqajy8v8k4BW34043qWOnruXaBp8U9Iq6nX/rkEZpjtqXRMhjiNZTb4XpVLtsSAtFG8omLkCr1IBinR1JTbGoJ+8HZd69sE69vKZ8aFijIefSKEFp3/sEEJNB0hS3qiu4Ng+9UPU+Wmzs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737573951; c=relaxed/simple; bh=F1IaxwlgzkyWXV7TDksnuXP1Jqz1CBh4zTlin+l5Hk8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UwifCzE/gtVJqNXo5fo4nrwx0gcDhibdz1YXGskqXCmw22hWIH91DnpNfHAydPvYZ1boDmbpieM4VF519r6q2fz/SpPb+GxDLHWLP71F5RsjqL+XT/Yi6aSZT5/JXu6fjH7ipo1tKHSdbKk/2NAzKJRsnW+BGZ0kE7o8o4YXRQ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=zgM0Rouz; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="zgM0Rouz" 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=2W+qfsEAUclS3rHGg1rqVyLJ0A2NtvBKn6a5gu/HE+Q=; b=zgM0RouzKSxSBhQv/D2XkgVoiw e8l+KkrofWnaCxW/VswXEPsvHyftp4soRON+mPixqjvrT2AITkMnzKN1rWqrs/Wxp2ezmVGKPkNdu cRnsRKEQEhOTsibHhZJqu0ckUkvOO94eOz1ecA+lN7FeJdsyhLkM8gfh64JDVS5eaN6h8D0yD3yEA cEFQnGMnIFZFu72GgIkctg9T67YAGC7LJr/Z891SSGX4Od3ZvoVqdBEJuQ0hCFTDxyZSzAvHl0BrE Nb1rs8od0pCKYzRUa6KI4B+cqA/Z762ewtE+2piYAXY/y4P7AaVEqDBqM6V7/8yoCfbVhxu3lK+1M wVmuLDGQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:44086) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1tagMA-0000Cl-1U; Wed, 22 Jan 2025 19:25:44 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.96) (envelope-from ) id 1tagM6-00059x-00; Wed, 22 Jan 2025 19:25:38 +0000 Date: Wed, 22 Jan 2025 19:25:37 +0000 From: "Russell King (Oracle)" To: Maxime Chevallier Cc: davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, thomas.petazzoni@bootlin.com, Andrew Lunn , Jakub Kicinski , Eric Dumazet , Paolo Abeni , linux-arm-kernel@lists.infradead.org, Christophe Leroy , Herve Codina , Florian Fainelli , Heiner Kallweit , Vladimir Oltean , =?iso-8859-1?Q?K=F6ry?= Maincent , Marek =?iso-8859-1?Q?Beh=FAn?= , Oleksij Rempel , =?iso-8859-1?Q?Nicol=F2?= Veronese , Simon Horman , mwojtas@chromium.org, Antoine Tenart , Rob Herring , Krzysztof Kozlowski , Conor Dooley Subject: Re: [PATCH net-next RFC v2 1/6] net: ethtool: common: Make BaseT a 4-lanes mode Message-ID: References: <20250122174252.82730-1-maxime.chevallier@bootlin.com> <20250122174252.82730-2-maxime.chevallier@bootlin.com> Precedence: bulk X-Mailing-List: devicetree@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: Sender: Russell King (Oracle) On Wed, Jan 22, 2025 at 06:55:17PM +0000, Russell King (Oracle) wrote: > On Wed, Jan 22, 2025 at 06:42:46PM +0100, Maxime Chevallier wrote: > > When referring to BaseT ethernet, we are most of the time thinking of > > BaseT4 ethernet on Cat5/6/7 cables. This is therefore BaseT4, although > > BaseT4 is also possible for 100BaseTX. This is even more true now that > > we have a special __LINK_MODE_LANES_T1 mode especially for Single Pair > > ethernet. > > > > Mark BaseT as being a 4-lanes mode. > > This is a problem: > > 1.4.50 10BASE-T: IEEE 802.3 Physical Layer specification for a 10 Mb/s > CSMA/CD local area network over two pairs of twisted-pair telephone > wire. (See IEEE Std 802.3, Clause 14.) > > Then we have the 100BASE-T* family, which can be T1, T2, T4 or TX. > T1 is over a single balanced twisted pair. T2 is over two pairs of > Cat 3 or better. T4 is over four pairs of Cat3/4/5. > > The common 100BASE-T* type is TX, which is over two pairs of Cat5. > This is sadly what the ethtool 100baseT link modes are used to refer > to. > > We do have a separate link mode for 100baseT1, but not 100baseT4. > > So, these ethtool modes that are of the form baseT so far are > describing generally two pairs, one pair in each direction. (T1 is > a single pair that is bidirectional.) > > It's only once we get to 1000BASE-T (1000baseT) that we get to an > ethtool link mode that has four lanes in a bidirectional fashion. > > So, simply redefining this ends up changing 10baseT and 100baseT from > a single lane in each direction to four lanes (and is a "lane" here > defined as the total number of pairs used for communication in both > directions, or the total number of lanes used in either direction. > > Hence, I'm not sure this makes sense. Looking at patch 2, I don't see why you need patch 1. It's not really improving the situation. Before the patch, the number of lanes for some BASE-T is wrong. After the patch, the number of lanes for some BASE-T is also wrong - just a different subset. I think you should drop this patch and just have patch 2. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!