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=-7.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 8D118C3526C for ; Sun, 20 Dec 2020 08:06:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 68B4A23A5E for ; Sun, 20 Dec 2020 08:06:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727270AbgLTIGj (ORCPT ); Sun, 20 Dec 2020 03:06:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45952 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726696AbgLTIGj (ORCPT ); Sun, 20 Dec 2020 03:06:39 -0500 Received: from mail-ej1-x635.google.com (mail-ej1-x635.google.com [IPv6:2a00:1450:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 54F5AC0613CF; Sun, 20 Dec 2020 00:05:58 -0800 (PST) Received: by mail-ej1-x635.google.com with SMTP id g20so9273405ejb.1; Sun, 20 Dec 2020 00:05:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=877C8AVqjHKt77VYGcchG1ePZwRG53cwgcE+oR4LK7w=; b=CzH1zD7ufC530iXBCdTSQZW8gQqFpDNbCJ6wgkZyJBssbN5CldUlVIAOXi8P0RvhRv 59zl21T16Ah6FqT+2h6eSdv5tpNlSqHWQ48pnDseAMiOiiwPfSma00AvKq2I7GiL3pxL mp9E6leksJMEyv/DNLv3elCfVr6hcOin1oewezdnIAyZuuR0YY72kAQXmtnVqQR6hY07 VK38yKSVK78eOmQO1oX29lZyxUazD7NPbImc/7QYdqnEjLz1pM2YzOlTtC/RvcmceSNw 25x4MvHWMXLcWNmuMp3VwMZHoLAkMPUxO6+f6yyyFKeH7jKojDEYwF7XkHSgA5/hHKaE pXAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=877C8AVqjHKt77VYGcchG1ePZwRG53cwgcE+oR4LK7w=; b=sAss1jbcV6e3MHFkwHgwGnDUU1K5VkrfB7jnQgSdQuujbO4QL18oKu28N0vwBaBlwU aKE5Gu1XijVvaEnrBhQjWPlb7jFZZ2Dopg9yQkOVlx6brc+7MrWCAUydcVurA4KaDAYb 2PB3E8jhlrdkx4RGaqy+E6bee97M57xzvX+FphdQLE9Mv5BsccDY4WNpMGIl/U9h9cYO lQkrPeNhZs16JKLimDClKGgcPFe22pEltgCqOeCia+cwKjyDSp9EGbLjNYHBMEVO57a9 JtGI1Wscm8Mpg30tciNvJf2oa7z/v1LspSFaLiyk/+GfXxNxhU75zs6OhZCxto9zyejB oJTg== X-Gm-Message-State: AOAM531p+z0ZYQJ4WN1+YeWKNrG1OK11pKUl687NXTe22loFgw9MSYjb EG0wtBMvHLYFy9lYWrIxO9Y= X-Google-Smtp-Source: ABdhPJynVMZurDmNSLenosgb8bMP8vdQ10DonTxTAGAoNGqz/N57p65eFrgSPRBf8uOb3zTFquW+sg== X-Received: by 2002:a17:906:4a47:: with SMTP id a7mr11035401ejv.345.1608451556949; Sun, 20 Dec 2020 00:05:56 -0800 (PST) Received: from skbuf ([188.25.2.120]) by smtp.gmail.com with ESMTPSA id cb21sm27615807edb.57.2020.12.20.00.05.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 20 Dec 2020 00:05:56 -0800 (PST) Date: Sun, 20 Dec 2020 10:05:55 +0200 From: Vladimir Oltean To: Rasmus Villemoes Cc: "David S . Miller" , Jakub Kicinski , netdev@vger.kernel.org, Zhao Qiang , Li Yang , Andrew Lunn , linux-kernel@vger.kernel.org, Vladimir Oltean Subject: Re: [PATCH net v2 1/3] ethernet: ucc_geth: set dev->max_mtu to 1518 Message-ID: <20201220080555.tgv3ndlkhzbvcpx7@skbuf> References: <20201218105538.30563-1-rasmus.villemoes@prevas.dk> <20201218105538.30563-2-rasmus.villemoes@prevas.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201218105538.30563-2-rasmus.villemoes@prevas.dk> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Dec 18, 2020 at 11:55:36AM +0100, Rasmus Villemoes wrote: > All the buffers and registers are already set up appropriately for an > MTU slightly above 1500, so we just need to expose this to the > networking stack. AFAICT, there's no need to implement .ndo_change_mtu > when the receive buffers are always set up to support the max_mtu. > > This fixes several warnings during boot on our mpc8309-board with an > embedded mv88e6250 switch: > > mv88e6085 mdio@e0102120:10: nonfatal error -34 setting MTU 1500 on port 0 > ... > mv88e6085 mdio@e0102120:10: nonfatal error -34 setting MTU 1500 on port 4 > ucc_geth e0102000.ethernet eth1: error -22 setting MTU to 1504 to include DSA overhead > > The last line explains what the DSA stack tries to do: achieving an MTU > of 1500 on-the-wire requires that the master netdevice connected to > the CPU port supports an MTU of 1500+the tagging overhead. > > Fixes: bfcb813203e6 ("net: dsa: configure the MTU for switch ports") > Cc: Vladimir Oltean > Reviewed-by: Andrew Lunn > Signed-off-by: Rasmus Villemoes > --- Reviewed-by: Vladimir Oltean