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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 98857C43217 for ; Thu, 21 Jan 2021 02:18:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7218F23787 for ; Thu, 21 Jan 2021 02:18:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404579AbhATXza (ORCPT ); Wed, 20 Jan 2021 18:55:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403926AbhATXVi (ORCPT ); Wed, 20 Jan 2021 18:21:38 -0500 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 45D73C061798 for ; Wed, 20 Jan 2021 14:36:11 -0800 (PST) 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=LK344BKhFxBCjto3A67yC1MJSrqRz9QtKcLEHfAkUSU=; b=h1IXcRLG4XDL+sEWWF4LWpkaF jOVCLO3EPWzcsZ6sthFkfJ6QDS1KPd2oyFW20t1JSYYMOGhPeaQrKWm6IjLlNmP9qUIGC6PBSigHI kTrOkAW701pnbIcKd6KK4p6ysWtkSuLpbEsRnUaRwgVh9Q3hdvQAtjl+GzHWHiBZl9oIfLxsinUFK FYzjDzC1N49Vy8Ve3yk+uXtXD+YTEO+QLw7cUY95UEWObhFsPFe/MDDqdBrfhekkp796rSnvtu7wQ yQLf7u3krI1/n2LISnOm35skNKkJGWrAOYvABGShk94YExP+h41gowu7PzrCbDlzSOjvQuTC/sn+7 EQZch3gZQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:50570) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1l2M52-0000gv-Cm; Wed, 20 Jan 2021 22:36:01 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1l2M50-0006Pg-RK; Wed, 20 Jan 2021 22:35:58 +0000 Date: Wed, 20 Jan 2021 22:35:58 +0000 From: Russell King - ARM Linux admin To: Ioana Ciornei Cc: Ioana Ciocoi Radulescu , Andrew Lunn , Heiner Kallweit , "David S. Miller" , Jakub Kicinski , "netdev@vger.kernel.org" Subject: Re: [PATCH net-next 3/3] net: dpaa2-mac: add backplane link mode support Message-ID: <20210120223558.GM1551@shell.armlinux.org.uk> References: <20210119153545.GK1551@shell.armlinux.org.uk> <20210120221900.i6esmk6uadgqpdtu@skbuf> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210120221900.i6esmk6uadgqpdtu@skbuf> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King - ARM Linux admin Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Jan 20, 2021 at 10:19:01PM +0000, Ioana Ciornei wrote: > On Tue, Jan 19, 2021 at 03:36:09PM +0000, Russell King wrote: > > Add support for backplane link mode, which is, according to discussions > > with NXP earlier in the year, is a mode where the OS (Linux) is able to > > manage the PCS and Serdes itself. > > Indeed, DPMACs in TYPE_BACKPLANE can have both their PCS and SerDes managed > by Linux (since the firmware is not touching these). > That being said, DPMACs in TYPE_PHY (the type that is already supported > in dpaa2-mac) can also have their PCS managed by Linux (no interraction > from the firmware's part with the PCS, just the SerDes). This is not what was discussed last year. It clearly shows in the slides that Bogdan sent in April 2020 "PCS Representation in Linux.pptx" page 4 that the firmware manages the PCS in TYPE_PHY and TYPE_FIXED mode. It was explained during the call that Linux must not access the internal MDIO nor touch the PCS _except_ when using TYPE_BACKPLANE mode. Touching the internal MDIO was stated as unsupported in other modes as the MC firmware will be performing MDIO accesses. > Also, with just the changes from this patch, a interface connected to a > DPMAC in TYPE_BACKPLANE is not even creating a phylink instance. It's > mainly because of this check from dpaa2-eth: > > if (dpaa2_eth_is_type_phy(priv)) { > err = dpaa2_mac_connect(mac); > > > I would suggest just dropping this patch. That is a recent change in net-next, but is not in my tree... In any case, if NXP have changed it such that, when in TYPE_PHY, the MC firmware no longer accesses the PCS and it is now safe to perform MDIO accesses, then we _still_ need this patch for older firmwares. In short, what you've put in your email does not tie up with the position that was discussed last year, and seems to me to be a total U-turn over what was being said. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!