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 603F53DEAEB; Wed, 11 Mar 2026 16:52:44 +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=1773247966; cv=none; b=Gbt4MEHPES/0wqibjcJJcpClycpwYC25j6v6YYk49QLZVXxJfPIIXer5v2KUgJFpT5ImsLTvq/K4oCcHqkwnMmtmidbJQZ8tXIlStn+uy78vvk/H90LDZTcHmpx64k85MmNhdNdyWGDcL333ocKSFbS2e4ak76Mxb2geW/j4ybs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773247966; c=relaxed/simple; bh=bWzneiJ4IHda7JaLKwlE8kyRQwSKFX283+EeLiYFgR0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SR7Z2NdoXJUuxfCcfwbJbQPNIDe1YzsbvCP4nyPGf5xSJe1TZQZi8n0+mpiTSJOyQh+Ch6gLMevTcRbKrQCgmGg9AcfWLXeJ1aMJHPnZ9eR8E7cL3ygCkm/NoF1pvgu/Q8DFGPd7svjh3aGGgvId99fxzuW7mdkPbJmEzdqj/Qw= 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=xBzYY7Vx; 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="xBzYY7Vx" 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=IOU4FYp2Mavg+4y+nURWKTXm/MUcQxgEkuD1zFPesWk=; b=xBzYY7VxoM62hImxr1VBygl6qr oXO4dWHonS5SVoay10fjrp5mvSX+n8VlxChnKaYb1MpmrjozaEEnAQmYpEj6UjSYXQFd425lUm6Tg mTjag/ClBwdKsN0ahAuIyOSvjZAQJwUX4mglydDLFlYpmgPwWQ+nNg47JrqXgsU2qQoBoSE/t3V63 9DFW7XUKiY+t7HJyxyqA4fhhcIJOJmj8zernVMGCWe0VXXB09Yg+Sw3zGovcT5qk1hk46N83NinPl ZWoWA24Dhm/H+1CC3cBNGHKSdEkeJ1pC7UMNMkDqmXuP/lX+p2bFy3rz/ybcz0XN93E1bGPuksF0u HhNOiWGA==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:52112) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1w0MnX-000000006g2-00uT; Wed, 11 Mar 2026 16:52:39 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1w0MnS-000000006OJ-43hU; Wed, 11 Mar 2026 16:52:34 +0000 Date: Wed, 11 Mar 2026 16:52:34 +0000 From: "Russell King (Oracle)" To: Andrew Lunn Cc: Naveen Mamindlapalli , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , netdev@vger.kernel.org, Donald Hunter , Jakub Kicinski , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Saeed Mahameed , Tariq Toukan , Leon Romanovsky , Andrew Lunn , Maxime Chevallier , Michael Chan , Hariprasad Kelam , Ido Schimmel , Danielle Ratson , linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org Subject: Re: [RFC net-next v2 0/6] ethtool: Generic loopback support Message-ID: References: <20260308124016.3134012-1-bjorn@kernel.org> <87tsupnjbc.fsf@all.your.base.are.belong.to.us> <0aa736b4-2c1c-4317-bcc1-1d4c9ad49380@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: <0aa736b4-2c1c-4317-bcc1-1d4c9ad49380@lunn.ch> Sender: Russell King (Oracle) On Wed, Mar 11, 2026 at 01:32:09PM +0100, Andrew Lunn wrote: > > > > With a SERDES component, the mapping becomes cleaner: > > > > component name supported > > > > MAC mac near-end > > > > SERDES serdes-ned near-end > > > > SERDES serdes-nea near-end > > > > SERDES serdes-fed far-end > > > > > > If Linux where to drive the SERDES, what part of Linux would it be? > > > Generic PHY? How does your SERDES hardware block fit into 802.3? Which > > > clause describes it? > > > > Hi Andrew, > > > > On OcteonTx2 SoC, the SerDes (GSERM) is a HW block integrated into the > > SoC die. It is not on an MDIO bus or any bus that Linux can enumerate. > > The block is fully managed by the firmware running on the SoC. The NIC > > driver configures it indirectly through firmware mailbox commands. > > > > The data path looks like: > > MAC (RPM) --- SerDes (GSERM) --- module/PHY > > > > In 802.3 terms, the closest match would be PMA. The GSERM handles > > serialization/deserialization and the analog front-end. > > A Linux Generic PHY is probably also PMA. > > 802.3 says very little about SERDES, it is not a well defined term. So > i think we want PCS and PMA, not SERDES as a loopback point. That's a good point. I'm wondeirng whether to change "serdes" / "SerDes" in my stmmac patches to be "pma". -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!