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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 63DBDC43441 for ; Mon, 26 Nov 2018 02:27:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1F21920855 for ; Mon, 26 Nov 2018 02:27:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b="kdIhdNFG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F21920855 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lunn.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726253AbeKZNTx (ORCPT ); Mon, 26 Nov 2018 08:19:53 -0500 Received: from vps0.lunn.ch ([185.16.172.187]:48773 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726101AbeKZNTw (ORCPT ); Mon, 26 Nov 2018 08:19:52 -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; bh=Ha3cDveggPtSD4sEpMeqIa8/ivd1C8QC695nLLy98EQ=; b=kdIhdNFGQc5COp/a/lOHenReGzfDhtxiREb4wzDtq/2NxT536J/jkmkiQX4cwTAU9qjdTTihJ3mic5oHae0IrbnNM/W2MfVfiMKMjECf106aQ3CY+vACHvBWUr+WuTz1NMw/vu1AwTcsc3iKEb2Wl7HB52rVu9tfZGSGyq2h66o=; Received: from andrew by vps0.lunn.ch with local (Exim 4.84_2) (envelope-from ) id 1gR6cB-0000G5-Dt; Mon, 26 Nov 2018 03:27:11 +0100 Date: Mon, 26 Nov 2018 03:27:11 +0100 From: Andrew Lunn To: Grygorii Strashko Cc: "David S. Miller" , netdev@vger.kernel.org, Sekhar Nori , linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org Subject: Re: [PATCH] net: ethernet: ti: cpsw: allow to configure min tx packet size Message-ID: <20181126022711.GD32164@lunn.ch> References: <20181125234315.28313-1-grygorii.strashko@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181125234315.28313-1-grygorii.strashko@ti.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Nov 25, 2018 at 05:43:15PM -0600, Grygorii Strashko wrote: > For proper VLAN packets forwarding CPSW driver uses min tx packet size of > 64bytes (VLAN_ETH_ZLEN, excluding ETH_FCS) which was corrected by > commit 9421c9015047 ("net: ethernet: ti: cpsw: fix min eth packet size"). > > Unfortunately, this breaks some industrial automation protocols, as > reported by TI customers [1], which can work only with min TX packet size > from 60 byte (ecluding FCS). Hi Grygorii excluding... > Hence, introduce module boot parameter "tx_packet_min" to allow configure > min TX packet size at boot time. Module parameters are generally not liked. What actually happens here with this lower limit? Does the hardware send runt packets? Does the protocol actually require runt packets? I'm just wondering if the module parameter can be avoided by setting this as the default. But we need to ensure ARP packets, which are smaller than the minimum MTU are correctly padded. Thanks Andrew