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=-10.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 7EA5FC433E0 for ; Sat, 27 Feb 2021 01:29:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B0E464EE7 for ; Sat, 27 Feb 2021 01:29:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230104AbhB0B2r (ORCPT ); Fri, 26 Feb 2021 20:28:47 -0500 Received: from szxga03-in.huawei.com ([45.249.212.189]:2910 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230063AbhB0B2n (ORCPT ); Fri, 26 Feb 2021 20:28:43 -0500 Received: from dggeme753-chm.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4DnTPC178Gz5W4x; Sat, 27 Feb 2021 09:25:51 +0800 (CST) Received: from [127.0.0.1] (10.69.26.252) by dggeme753-chm.china.huawei.com (10.3.19.99) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2106.2; Sat, 27 Feb 2021 09:27:54 +0800 Subject: Re: [PATCH net] net: phy: fix save wrong speed and duplex problem if autoneg is on To: Andrew Lunn CC: , , , , , , Guangbin Huang References: <1614325482-25208-1-git-send-email-tanhuazhong@huawei.com> From: Huazhong Tan Message-ID: Date: Sat, 27 Feb 2021 09:27:54 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.69.26.252] X-ClientProxiedBy: dggeme704-chm.china.huawei.com (10.1.199.100) To dggeme753-chm.china.huawei.com (10.3.19.99) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/2/27 8:53, Andrew Lunn wrote: > On Fri, Feb 26, 2021 at 03:44:42PM +0800, Huazhong Tan wrote: >> From: Guangbin Huang >> >> If phy uses generic driver and autoneg is on, enter command >> "ethtool -s eth0 speed 50" will not change phy speed actually, but >> command "ethtool eth0" shows speed is 50Mb/s because phydev->speed >> has been set to 50 and no update later. >> >> And duplex setting has same problem too. >> >> However, if autoneg is on, phy only changes speed and duplex according to >> phydev->advertising, but not phydev->speed and phydev->duplex. So in this >> case, phydev->speed and phydev->duplex don't need to be set in function >> phy_ethtool_ksettings_set() if autoneg is on. >> >> Signed-off-by: Guangbin Huang >> Signed-off-by: Huazhong Tan > I'm not sure, but i think this happens after > > commit 51e2a3846eab18711f4eb59cd0a4c33054e2980a > Author: Trent Piepho > Date: Wed Sep 24 10:55:46 2008 +0000 > > PHY: Avoid unnecessary aneg restarts > > The PHY's aneg is configured and restarted whenever the link is brought up, > e.g. when DHCP is started after the kernel has booted. This can take the > link down for several seconds while auto-negotiation is redone. > > If the advertised features haven't changed, then it shouldn't be necessary > to bring down the link and start auto-negotiation over again. > > genphy_config_advert() is enhanced to return 0 when the advertised features > haven't been changed and >0 when they have been. > > genphy_config_aneg() then uses this information to not call > genphy_restart_aneg() if there has been no change. > > Before then, i think autoneg was unconditionally restarted, and so the > speed would get overwritten when autoneg completed. After this patch, > since autoneg is not being changed when only speed is set, autoneg is > not triggered. > > Andrew Thanks. > .