From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753405AbbGNU2y (ORCPT ); Tue, 14 Jul 2015 16:28:54 -0400 Received: from smtp3.mail.ru ([94.100.179.58]:44117 "EHLO smtp3.mail.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752666AbbGNU2v (ORCPT ); Tue, 14 Jul 2015 16:28:51 -0400 Subject: Re: [PATCH 2/3] of_mdio: add new DT property 'managed' to specify the PHY management type To: Florian Fainelli , netdev References: <55A5424D.4030809@list.ru> <55A5432C.1080609@list.ru> <55A54C3A.1040403@gmail.com> Cc: Linux kernel , Sebastien Rannou , Arnaud Ebalard , Stas Sergeev , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Grant Likely , "devicetree@vger.kernel.org" From: Stas Sergeev Message-ID: <55A57062.80703@list.ru> Date: Tue, 14 Jul 2015 23:26:10 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.0.1 MIME-Version: 1.0 In-Reply-To: <55A54C3A.1040403@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Spam: Not detected X-Mras: Ok Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 14.07.2015 20:51, Florian Fainelli пишет: > On 14/07/15 10:13, Stas Sergeev wrote: >> Currently the PHY management type is selected by the MAC driver arbitrary. >> The decision is based on the presence of the "fixed-link" node and on a >> will of the driver's authors. >> This caused a regression recently, when mvneta driver suddenly started >> to use the in-band status for auto-negotiation on fixed links. >> It appears the auto-negotiation may not work when expected by the MAC driver. >> Sebastien Rannou explains: >> << Yes, I confirm that my HW does not generate an in-band status. AFAIK, it's >> a PHY that aggregates 4xSGMIIs to 1xQSGMII ; the MAC side of the PHY (with >> inband status) is connected to the switch through QSGMII, and in this context >> we are on the media side of the PHY. >> >> https://lkml.org/lkml/2015/7/10/206 >> >> This patch introduces the new string property 'managed' that allows >> the user to set the management type explicitly. >> The supported values are: >> "auto" - default. Uses either MDIO or nothing, depending on the presence >> of the fixed-link node >> "mdio" - use MDIO >> "in-band-status" - use in-band status >> "none" - use fixed-link description > I thought we agreed in the last thread that "mdio" was implied whenever > a proper PHY phandle to a device sitting on MDIO bus is used and that > "auto" did not make much sense unless we were also describing how to do > this auto-negotiation completely? Exactly not: --- > If we would implement autoneg outside of the fixed-link, > then its semantic would likely be > autoneg = "mdio" | "in-band" | "off" Right, if auto-negotiation was defined outside of fixed-link, that is indeed how I would also specify this. --- That's why I implemented it the way you see. But as you changed your mind, I'll remove "mdio". > As mentioned below, "mdio" is redundant with finding a "phy-handle", > and "auto" is not specific enough to be useful to a consumer of this > information. I prefer to keep "auto", as otherwise we'll have the default value (when the option is not specified) never achievable when the option _is_ specified, which is probably not very good. But I can remove "none" instead, leaving only "in-band-status" and "auto". Ok? Of course one can propose to completely ignore that option in presence of MDIO, but I wonder why not to allow for example to opt for in-band status even if you have MDIO? So if we want this option to play nicely with MDIO, as opposed to being entirely overridden, then "auto" still makes sense IMO.