From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF01BC2D0C2 for ; Fri, 3 Jan 2020 09:27:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A6A5E217F4 for ; Fri, 3 Jan 2020 09:27:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="xY0zM+Ce" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727462AbgACJ1b (ORCPT ); Fri, 3 Jan 2020 04:27:31 -0500 Received: from pandora.armlinux.org.uk ([78.32.30.218]:38336 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726640AbgACJ1a (ORCPT ); Fri, 3 Jan 2020 04:27:30 -0500 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=TFFNUpBqrHSpyurnMmcanTS7uqHtMMP0ooKKfVEFBeA=; b=xY0zM+CeBrM/vokDa80g5TsP7 yMjSfuLAZNBHGfXQAzrjsYJ7w7huIQs1MR7Sp6VCRFpgEoFjmC42WtfI2jiFoR+fNbT2+o4r6OucS USrfgGGAkKAXCVf5z+KrasALMVjdLAyuj4TLWWDQ6GDTbr2tSUhQ+opAE/GdtWclzCiNsBGSgK9qD IbxETDnQrTZ/gXelOAW1D92iDqK/VA14h1U21WvcBBR62Yuu9GVlznsWuOvF6vYfw/a2sjtt3cfXD MAZEPTQwzcLobUe3JwBAFGRdwewng1VE1RWSosx2GOa/uR4DOMv257cO0pmpE3wNKKTBPDKhgLrDu N+7y8Bs/Q==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:33388) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1inJEp-0001FV-9X; Fri, 03 Jan 2020 09:27:23 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1inJEk-00030q-7h; Fri, 03 Jan 2020 09:27:18 +0000 Date: Fri, 3 Jan 2020 09:27:18 +0000 From: Russell King - ARM Linux admin To: "Madalin Bucur (OSS)" Cc: "devicetree@vger.kernel.org" , "davem@davemloft.net" , "netdev@vger.kernel.org" , "andrew@lunn.ch" , "f.fainelli@gmail.com" , "hkallweit1@gmail.com" , "shawnguo@kernel.org" Subject: Re: [PATCH 1/6] net: phy: add interface modes for XFI, SFI Message-ID: <20200103092718.GB25745@shell.armlinux.org.uk> References: <1576768881-24971-1-git-send-email-madalin.bucur@oss.nxp.com> <1576768881-24971-2-git-send-email-madalin.bucur@oss.nxp.com> <20191219172834.GC25745@shell.armlinux.org.uk> <20191223120730.GO25745@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Jan 03, 2020 at 07:01:50AM +0000, Madalin Bucur (OSS) wrote: > > -----Original Message----- > > From: Russell King - ARM Linux admin > > Sent: Monday, December 23, 2019 2:08 PM > > To: Madalin Bucur > > Cc: davem@davemloft.net; netdev@vger.kernel.org; andrew@lunn.ch; > > f.fainelli@gmail.com; hkallweit1@gmail.com; shawnguo@kernel.org; > > devicetree@vger.kernel.org > > Subject: Re: [PATCH 1/6] net: phy: add interface modes for XFI, SFI > > > > On Thu, Dec 19, 2019 at 06:32:51PM +0000, Madalin Bucur wrote: > > > 10GBase-R could be used as a common nominator but just as well 10G and > > > remove the rest while we're at it. There are/may be differences in > > > features, differences in the way the HW is configured (the most > > > important aspect) and one should be able to determine what interface > > > type is in use to properly configure the HW. SFI does not have the CDR > > > function in the PMD, relying on the PMA signal conditioning vs the XFI > > > that requires this in the PMD. > > > > I've now found a copy of INF-8077i on the net, which seems to be the > > document that defines XFI. The definition in there seems to be very > > similar to SFI in that it is an electrical specification, not a > > protocol specification, and, just like SFI, it defines the electrical > > characteristics at the cage, not at the serdes. Therefore, the effects > > of the board layout come into play to achieve compliance with XFI. > > I think we're missing the point here: we need to start from the device > tree and that is supposed to describe the board, the hardware, not to > configure the software. Please re-read the paragraph above in this key: > the device tree needs to describe the HW features, those electrical > properties you are discussing above. The fact that we use a certain > protocol over it, by choice in software, does not change the HW and it > should not change the device tree describing it. phy_interface_t does *NOT* describe the electrical properties of the link; it describes the protocol. The protocol for 10GBASE-R, SFI and XFI are *all* the same. Therefore, phy_interface_t does *not* distinguish between these. Yes, DT may need to describe the electrical properties. That needs to be done independently of the phy_interface_t and therefore phy-mode definition. Just like it is done for SATA interfaces that need the eye mask (electrical properties of the serdes) adjusted for the board. > > Just like SFI, XFI can be used with multiple different underlying > > protocols. I quote: > > > > "The XFI interface is designed to support SONET OC-192, > > IEEE.Std-802.3ae, 10GFC and G.709(OTU-2) applications." > > > > Therefore, to describe 10GBASE-R as "XFI" is most definitely incorrect. > > 10GBASE-R is just _one_ protocol that can be run over XFI, but it is > > not the only one. > > Exactly why the chip to chip interface described by the device tree needs > to be xfi not 10GBASE-R, Sorry no. Merely specifying "xfi" does not tell you what you need to do to achieve XFI compliance at the point defined in INF8077i. Plus, XFI can also be protocols _other_ than 10GBASE-R. Claiming that "XFI" properly defines the interface is utter rubbish. It does not. XFI defines the electrical characteristics *only* and not the underlying protocol. It is not limited to 10GBASE-R, but includes other protocols as well. XFI is not a phy interface type. Sorry. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up