From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay4-d.mail.gandi.net (relay4-d.mail.gandi.net [217.70.183.196]) (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 97D82186A; Thu, 23 Jan 2025 10:47:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.196 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737629233; cv=none; b=dt3EKVsr/xZ16YMt4QLeLEUJCzxtuEDjjeFWvB+RL0GtBz+UvUxUSWONSWg6c08xtdUd/zPjHMTYs8wZf8PNWy+kDvyO1UwmnOtERXjWU9ILvxNWcSLa2yxGoNdiymbVUqf1kzP52hABfIlTkCaIfKjP1MAforjFpJT+80K9Etc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737629233; c=relaxed/simple; bh=ldv2yx7//HvG97ZMakEiZJCNXqlwF//BRONJRWhNM/o=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=gi0QfL7oCS8U2+EvmLICrddV3LUG+xFh+6qC0VsF2Vi3S1qVWAjq2fteGg/MTS5zM20HPWpGQGQBhACkFmftpRcYFb2x62XpocbG/jTBMz2M7hhT5Lv6hEsRWuLcn6ZRj0xb6nC3+RDq3RKuf6T2r4MqzdwOPzN+WCZCoXTRhGE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=DUuzo9eH; arc=none smtp.client-ip=217.70.183.196 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="DUuzo9eH" Received: by mail.gandi.net (Postfix) with ESMTPSA id 33211E000C; Thu, 23 Jan 2025 10:47:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1737629228; 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=z57cSE1YbxqFMvNXpCY9G1ml/Qmrt4h2lF0Z1wJAZeg=; b=DUuzo9eHub7/9PHurqPsH7DVY2E29qZysu/JXIZMuv4LVRmHZ/6ECt7tt2VnNLXJ8aNBEH R78LqtD/c5I3LNz2jM/92soLfSDNIPPM5ibHpyBjO1fdyWXFT9gJRk60J18pmwOuoXYaqC JarofkUBD6J08p72p8SEVzURzJPyLC27BqGGutcCUADiDKWxPe7CZ3QqOXFcyvOWPsmRW8 pSdoP8nSBStB+hrABkz+8Ib9Yzxqr1x0j89/qHoNet9qPbWjnd4GlI2fwcte6KT6/bxL0/ 7gKbf//tehBgA1qPdBCApsdvuWANLeTEO1C1EfEavc02x7DPVFb68LvC60LkBA== Date: Thu, 23 Jan 2025 11:47:02 +0100 From: Maxime Chevallier To: "Russell King (Oracle)" 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 , =?UTF-8?B?S8O2cnk=?= Maincent , Marek =?UTF-8?B?QmVow7pu?= , Oleksij Rempel , =?UTF-8?B?Tmljb2zDsg==?= 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: <20250123114702.2c69f49f@fedora.home> In-Reply-To: References: <20250122174252.82730-1-maxime.chevallier@bootlin.com> <20250122174252.82730-2-maxime.chevallier@bootlin.com> Organization: Bootlin X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-redhat-linux-gnu) 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-Transfer-Encoding: 7bit X-GND-Sasl: maxime.chevallier@bootlin.com Hello Russell, On Wed, 22 Jan 2025 18:55:17 +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. > I'm fine with your justification, so let's simplify and drop that patch then. That should also avoid the lanes/pairs confusion as well. Thanks for the feedback ! Maxime