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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 3E749C433DF for ; Wed, 20 May 2020 12:47:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A99020758 for ; Wed, 20 May 2020 12:47:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="OTkEIzZ0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726791AbgETMrp (ORCPT ); Wed, 20 May 2020 08:47:45 -0400 Received: from fllv0015.ext.ti.com ([198.47.19.141]:53780 "EHLO fllv0015.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726224AbgETMro (ORCPT ); Wed, 20 May 2020 08:47:44 -0400 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id 04KClbBh051869; Wed, 20 May 2020 07:47:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1589978857; bh=AqvDDiNjhhJJhH+2Iuzf1KQzaudYFdiwJFg+rGhVDtI=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=OTkEIzZ04akVj95vxKCo/fEJGIogs0keHAhPYz7nPnkDbD9MNwcZy6km1ASENQhXj D6itTR60obTCXXgXw1gA4b/TA1wES0D9ffHvV5oP3NJKS2T1XikhKIn5xHgxAXfz+y 4/3LADkD7ZB8L2Up7CcpZ0Tr2705zv0P0TjZb2RU= Received: from DFLE113.ent.ti.com (dfle113.ent.ti.com [10.64.6.34]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 04KClbLc110251 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 20 May 2020 07:47:37 -0500 Received: from DFLE115.ent.ti.com (10.64.6.36) by DFLE113.ent.ti.com (10.64.6.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3; Wed, 20 May 2020 07:47:36 -0500 Received: from lelv0326.itg.ti.com (10.180.67.84) by DFLE115.ent.ti.com (10.64.6.36) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3 via Frontend Transport; Wed, 20 May 2020 07:47:36 -0500 Received: from [10.250.74.234] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0326.itg.ti.com (8.15.2/8.15.2) with ESMTP id 04KClaIm129871; Wed, 20 May 2020 07:47:36 -0500 Subject: Re: [next-queue RFC 0/4] ethtool: Add support for frame preemption To: Vinicius Costa Gomes , Andre Guedes , CC: , , , , References: <20200516012948.3173993-1-vinicius.gomes@intel.com> <158992799425.36166.17850279656312622646@twxiong-mobl.amr.corp.intel.com> <87y2pnmr83.fsf@intel.com> From: Murali Karicheri Message-ID: <13d8b7ba-8afd-cb67-c782-56aff1412bcd@ti.com> Date: Wed, 20 May 2020 08:47:36 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <87y2pnmr83.fsf@intel.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Vinicius, On 5/19/20 7:37 PM, Vinicius Costa Gomes wrote: > Andre Guedes writes: > >> Hi, >> >> Quoting Vinicius Costa Gomes (2020-05-15 18:29:44) >>> One example, for retrieving and setting the configuration: >>> >>> $ ethtool $ sudo ./ethtool --show-frame-preemption enp3s0 >>> Frame preemption settings for enp3s0: >>> support: supported >>> active: active >> >> IIUC the code in patch 2, 'active' is the actual configuration knob that >> enables or disables the FP functionality on the NIC. >> >> That sounded a bit confusing to me since the spec uses the term 'active' to >> indicate FP is currently enabled at both ends, and it is a read-only >> information (see 12.30.1.4 from IEEE 802.1Q-2018). Maybe if we called this >> 'enabled' it would be more clear. > > Good point. Will rename this to "enabled". > >> >>> supported queues: 0xf >>> supported queues: 0xe >>> minimum fragment size: 68 >> >> I'm assuming this is the configuration knob for the minimal non-final fragment >> defined in 802.3br. >> >> My understanding from the specs is that this value must be a multiple from 64 >> and cannot assume arbitrary values like shown here. See 99.4.7.3 from IEEE >> 802.3 and Note 1 in S.2 from IEEE 802.1Q. In the previous discussion about FP, >> we had this as a multiplier factor, not absolute value. > > I thought that exposing this as "(1 + N)*64" (with 0 <= N <= 3) that it > was more related to what's exposed via LLDP than the actual capabilities > of the hardware. And for the hardware I have actually the values > supported are: (1 + N)*64 + 4 (for N = 0, 1, 2, 3). > > So I thought I was better to let the driver decide what values are > acceptable. > > This is a good question for people working with other hardware. > > AM65 CPSW supports this as a multiple of 64. Since this ethtool configuration is for the hardware, might want to make it as a multiple of 64. Murali -- Murali Karicheri Texas Instruments