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=-2.1 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 13910C2D0BF for ; Tue, 17 Dec 2019 23:25:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B832A21582 for ; Tue, 17 Dec 2019 23:25:36 +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="x2msvNHU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726539AbfLQXZf (ORCPT ); Tue, 17 Dec 2019 18:25:35 -0500 Received: from pandora.armlinux.org.uk ([78.32.30.218]:35502 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726072AbfLQXZe (ORCPT ); Tue, 17 Dec 2019 18:25:34 -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=+ZRgwQu/8qI//tu+qKKPwWQ1BDjAVgEdedDApeEuiZE=; b=x2msvNHUyof3OiOD7rm/owvx/ GYhGhesmWA4ThYMegAxSZDkg48O9V23bbMVm8hppJRr3CXP4JJFwRC2ujRLwn4VP9UkZ0OdLmhy2f 3wN8UA+/mBi7FV4LihERQQw6+jneYC1OXUCvh8pytZ3I7f8YMuAdGQhhSfQ032z7GSEtfZ+Oz22sy Glu9m6XDY4tSGiXJagB9iyS2QIUYFSVS8IGLF4TXMolD/McNJc0u5QP+2x07dIvD8VRFnlkp88Qq6 BccwBYpnOMMqB4bdD8OOuzzAVmGQzHzZvhi7oasYfcgw9Om2FbKqh8A55eeQSJMBUKYmRO2/ETtdy uF8a43l5Q==; Received: from shell.armlinux.org.uk ([2002:4e20:1eda:1:5054:ff:fe00:4ec]:50250) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ihMDQ-0000PL-UH; Tue, 17 Dec 2019 23:25:21 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1ihMDL-0003mN-Q1; Tue, 17 Dec 2019 23:25:15 +0000 Date: Tue, 17 Dec 2019 23:25:15 +0000 From: Russell King - ARM Linux admin To: Vladimir Oltean Cc: davem@davemloft.net, jakub.kicinski@netronome.com, andrew@lunn.ch, f.fainelli@gmail.com, vivien.didelot@gmail.com, alexandru.marginean@nxp.com, claudiu.manoil@nxp.com, xiaoliang.yang_1@nxp.com, yangbo.lu@nxp.com, netdev@vger.kernel.org, alexandre.belloni@bootlin.com, horatiu.vultur@microchip.com, Vladimir Oltean Subject: Re: [RFC PATCH v2 3/8] net: phylink: call mac_an_restart for SGMII/QSGMII inband interfaces too Message-ID: <20191217232515.GR25745@shell.armlinux.org.uk> References: <20191217221831.10923-1-olteanv@gmail.com> <20191217221831.10923-4-olteanv@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191217221831.10923-4-olteanv@gmail.com> 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 Wed, Dec 18, 2019 at 12:18:26AM +0200, Vladimir Oltean wrote: > From: Vladimir Oltean > > It doesn't quite make sense why restarting the AN process should be > unique to 802.3z (1000Base-X) modes. It is valid to put an SGMII PCS in > in-band AN mode, therefore also make PHYLINK re-trigger an > auto-negotiation if needed. The question I'd ask is how is that actually achieved on the link? It makes sense for 1000base-X because either end can drop the ACK bit to cause a renegotiation to occur, but it makes no sense for SGMII. In SGMII: 1) there is no advertisement from the MAC to the PHY 2) the PHY is merely informing the MAC of the results of negotiation Attempting to trigger a renegotiation at the MAC end does nothing useful for SGMII, it doesn't cause the PHY to renegotiate with its link partner. The whole point of SGMII over 1000base-X is that the PHY informs the MAC using in-band signalling what the results of negotiation were on the media side of the PHY. SGMII provides no way to control the advertisement. -- 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