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, 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 9B2FCC43331 for ; Tue, 12 Nov 2019 13:57:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 646DC21783 for ; Tue, 12 Nov 2019 13:57:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b="v9EHK/iS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727338AbfKLN5P (ORCPT ); Tue, 12 Nov 2019 08:57:15 -0500 Received: from vps0.lunn.ch ([185.16.172.187]:35904 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727324AbfKLN5P (ORCPT ); Tue, 12 Nov 2019 08:57:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Sender: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=LLceIVnPXWZv1KmyJrA5OpHI8D6HpTcyMK8+3C0Ntvc=; b=v9EHK/iSNAsx9Wmh0cF4xEmgLE KFLtb3kqul3U7GmVKj/PHZ7QKbGfK26yPctYQJAjW537CrwNzV6tF+d/Mdc89DXMAzGeYLWIVLcdc q4r1CFS0W5omSM3uYUTODwR+gu+uJKf2dcRbOh+boMQAn/MBpzKJgxtJYvQSqKiVakwE=; Received: from andrew by vps0.lunn.ch with local (Exim 4.92.2) (envelope-from ) id 1iUWfP-0001ki-3Y; Tue, 12 Nov 2019 14:57:11 +0100 Date: Tue, 12 Nov 2019 14:57:11 +0100 From: Andrew Lunn To: Vladimir Oltean Cc: Jakub Kicinski , "David S. Miller" , Alexandre Belloni , Florian Fainelli , Vivien Didelot , Joergen Andreasen , "Allan W. Nielsen" , Horatiu Vultur , Claudiu Manoil , netdev , Vladimir Oltean Subject: Re: [PATCH net-next 06/12] net: mscc: ocelot: adjust MTU on the CPU port in NPI mode Message-ID: <20191112135711.GJ5090@lunn.ch> References: <20191112124420.6225-1-olteanv@gmail.com> <20191112124420.6225-7-olteanv@gmail.com> <20191112135107.GH5090@lunn.ch> 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 Tue, Nov 12, 2019 at 03:52:51PM +0200, Vladimir Oltean wrote: > On Tue, 12 Nov 2019 at 15:51, Andrew Lunn wrote: > > > > On Tue, Nov 12, 2019 at 02:44:14PM +0200, Vladimir Oltean wrote: > > > From: Vladimir Oltean > > > > > > When using the NPI port, the DSA tag is passed through Ethernet, so the > > > switch's MAC needs to accept it as it comes from the DSA master. Increase > > > the MTU on the external CPU port to account for the length of the > > > injection header. > > > > I think this is the only DSA driver which needs to do this. Generally, > > the port knows it is adding/removing the extra header, and so > > magically accepts bigger frames. > > > > Where i have seen issues is the other end, the host interface. It > > sometimes drops 'full MTU' frames because the DSA header makes the > > frame too big. > > > > No, that worked out of the box because DSA adjusts the MTU of the > master interface by the amount of bytes specified in the overhead of > the tagger. Yes, i added that code, after having to modify too many MAC drivers! Andrew