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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 F1E20C433E0 for ; Tue, 16 Feb 2021 08:44:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A859264E08 for ; Tue, 16 Feb 2021 08:44:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229970AbhBPIn1 (ORCPT ); Tue, 16 Feb 2021 03:43:27 -0500 Received: from esa.microchip.iphmx.com ([68.232.153.233]:43134 "EHLO esa.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229903AbhBPIjP (ORCPT ); Tue, 16 Feb 2021 03:39:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1613464754; x=1645000754; h=message-id:subject:from:to:cc:date:in-reply-to: references:mime-version:content-transfer-encoding; bh=Nq9yQxYqOwgVE/65sX+lXgjLa7zjX+KlCrzRlYHvhQs=; b=vGjwDVf5ZswNQj53LopgZf7VVuNK4TOiydcBOadih3KcrvquHAH9gufE 6n5d3iYiP2VpkYclZtmxu/E/8vQpyaVcaklBLfV70GmwwRDNP4afNHRxd OyXQGMl85yBmBOpmSjhufZh46h7CKqj91fW4aHlRuxRXfqjkir1zohAW5 gBvnrwDOXmVsPfzKQ3xLkMwhawguD3Jj8dpqu8EkW5tttqKHYGkZnhcm/ dJvtZOqTB7AustwMEK+XALMNuBF59AU8bdqyOG48qRS3babikOyQNd1z2 k41QtWN0B6i8S0/SdT2zQ2u85MCrLcXUgnQH9cw75TRzIMC27I0VeoFnJ g==; IronPort-SDR: Sy1A1/+uQtytlMN+4nwYKEvrFZK0Jaeu7b9LDMpseh76HQgCs56yX4xguv/ew7lZJE1jC6mui1 AzaFU56nbzHafne42RLxcSYhou8AW1eGbQ8Wd3DBzlGLyMaBw4OlLtEGRMSBZIqDvvMKj9h9YZ iMNxD3Q4coDBC734N4+UfvfEEROWN1A0F3rIdA6qLqKXPF/YHnHLX2oRX5rG8X9X0Pybz2UczT wbz7mytxUUshiWSE3LSk3n7AO58Tn26+NCxBBD4GjugxowlTWhvN2sUARRxHlC9y4iO+fNAS+R 5Do= X-IronPort-AV: E=Sophos;i="5.81,183,1610434800"; d="scan'208";a="115234890" Received: from smtpout.microchip.com (HELO email.microchip.com) ([198.175.253.82]) by esa1.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 16 Feb 2021 01:37:59 -0700 Received: from chn-vm-ex04.mchp-main.com (10.10.85.152) by chn-vm-ex04.mchp-main.com (10.10.85.152) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 16 Feb 2021 01:37:59 -0700 Received: from tyr.hegelund-hansen.dk (10.10.115.15) by chn-vm-ex04.mchp-main.com (10.10.85.152) with Microsoft SMTP Server id 15.1.1979.3 via Frontend Transport; Tue, 16 Feb 2021 01:37:57 -0700 Message-ID: Subject: Re: [PATCH v14 2/4] phy: Add media type and speed serdes configuration interfaces From: Steen Hegelund To: Andrew Lunn , Kishon Vijay Abraham I CC: Vinod Koul , Alexandre Belloni , Lars Povlsen , Bjarni Jonasson , Microchip UNG Driver List , , Date: Tue, 16 Feb 2021 09:37:56 +0100 In-Reply-To: References: <20210210085255.2006824-1-steen.hegelund@microchip.com> <20210210085255.2006824-3-steen.hegelund@microchip.com> <04d91f6b-775a-8389-b813-31f7b4a778cb@ti.com> <704b850f-9345-2e36-e84b-b332fed22270@ti.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.4 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andrew and Kishon, On Mon, 2021-02-15 at 15:07 +0100, Andrew Lunn wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you > know the content is safe > > On Mon, Feb 15, 2021 at 05:25:10PM +0530, Kishon Vijay Abraham I > wrote: > > Okay. Is it going to be some sort of manual negotiation where the > > Ethernet controller invokes set_speed with different speeds? Or the > > Ethernet controller will get the speed using some out of band > > mechanism > > and invokes set_speed once with the actual speed? > > Hi Kishon > > There are a few different mechanism possible. > > The SFP has an EEPROM which contains lots of parameters. One is the > maximum baud rate the module supports. PHYLINK will combine this > information with the MAC capabilities to determine the default speed. > > The users can select the mode the MAC works in, e.g. 1000BaseX vs > 2500BaseX, via ethtool -s. Different modes needs different speeds. > > Some copper PHYs will change there host side interface baud rate when > the media side interface changes mode. 10GBASE-X for 10G copper, > 5GBase-X for 5G COPPER, 2500Base-X for 2.5G copper, and SGMII for > old school 10/100/1G Ethernet. > > Mainline Linux has no support for it, but some 'vendor crap' will do > a > manual negotiation, simply trying different speeds and see if the > SERDES establishes link. There is nothing standardised for this, as > far as i know. > >     Andrew Yes, in case I mention the only way to ensure communication is human intervention to set the speed to the highest common denominator. BR Steen