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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 625F8C1B08C for ; Thu, 15 Jul 2021 13:09:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 49852613C1 for ; Thu, 15 Jul 2021 13:09:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237198AbhGONL7 (ORCPT ); Thu, 15 Jul 2021 09:11:59 -0400 Received: from vps0.lunn.ch ([185.16.172.187]:56942 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229624AbhGONL6 (ORCPT ); Thu, 15 Jul 2021 09:11:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Disposition:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:From:Sender:Reply-To:Subject: Date:Message-ID:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Content-Disposition:In-Reply-To:References; bh=crnV8WiEsXkYRDOXGKgUcdIiSuJkX3wBykL63bhych8=; b=PGteHXKTX7HAeE/TZ52+tsm07W 9QaWn3GT1Ew2am1IQgb/Zg5KPHd/9AGcLQqee+1eG+bxEDBAFTV7c/px87wrf5mwaGNIsIC3z7NCQ NaGzfMgVGeRCL9F2tbD5hiTf4Ftph5Gc81Zxe1tEhfrj79pWa39uX3K1d0pMfX/t7tSQ=; Received: from andrew by vps0.lunn.ch with local (Exim 4.94.2) (envelope-from ) id 1m416j-00DUS1-Gx; Thu, 15 Jul 2021 15:08:53 +0200 Date: Thu, 15 Jul 2021 15:08:53 +0200 From: Andrew Lunn To: Vladimir Oltean Cc: Lino Sanfilippo , woojung.huh@microchip.com, UNGLinuxDriver@microchip.com, vivien.didelot@gmail.com, f.fainelli@gmail.com, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum Message-ID: References: <20210714191723.31294-1-LinoSanfilippo@gmx.de> <20210714191723.31294-3-LinoSanfilippo@gmx.de> <20210714194812.stay3oqyw3ogshhj@skbuf> <20210715065455.7nu7zgle2haa6wku@skbuf> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210715065455.7nu7zgle2haa6wku@skbuf> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org > - If we inherit NETIF_F_HW_CSUM from the master for tail taggers, it is > actively detrimential to keep this feature enabled, as proven my Lino. > As for header taggers, I fail to see how this would be helpful, since > the DSA master would always fail to see the real IP header (it has > been pushed to the right by the DSA tag), and therefore, the DSA > master offload would be effectively bypassed. The Marvell MACs know about DSA and should be able to perform hardware checksumming. It is a long time since i looked at how this works, but i think there is a field in the descriptor which gets set with the offset to the IP header, so it work for DSA as well as EDSA. I _think_ Broadcom MACs also know about Broadcom tags and can do the right thing. So we need to be a bit careful here to prevent performance regressions for same vendor MAC+Switch combinations. Andrew