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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0804CC433F5 for ; Wed, 8 Dec 2021 16:49:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237298AbhLHQxL (ORCPT ); Wed, 8 Dec 2021 11:53:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234667AbhLHQxK (ORCPT ); Wed, 8 Dec 2021 11:53:10 -0500 Received: from mail-ed1-x536.google.com (mail-ed1-x536.google.com [IPv6:2a00:1450:4864:20::536]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0745C061746 for ; Wed, 8 Dec 2021 08:49:38 -0800 (PST) Received: by mail-ed1-x536.google.com with SMTP id r11so10211922edd.9 for ; Wed, 08 Dec 2021 08:49:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=yTtKz7qgpmyTBZxPy8RkUofqfaCY79MXklJwBcQAysU=; b=KyIHFoSAEwYaB/6ADRf7T90/f9CJP+rYuoJKDdG/cZ5VtKsHsKskhR246kCl+3m+f/ Z2Q+AR7wxOUCiNKpGLA3d+Ixe8LxwovqmrxRAd3XjJUDGxtijGts/+snIIpOflBnRUR+ TBXybg1thvIl+Vn1TrkCmaWHTs1or/Tw8lF9cQlBzBrzqufZq0YTP6BcL32N1puj7Rne N4zxlN2Zxj4n6/rADPtR8u0YAzajY10hzOCTHsHsaJhRNewUpvxq5Q6/gc4/Jd6q+szO qKjQI9CzxJwhmD4yJGoRDru/CgXE292svrfnSnvO4P9APNqy+qyrILk+VVYFJbm01gPI 5FJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=yTtKz7qgpmyTBZxPy8RkUofqfaCY79MXklJwBcQAysU=; b=jBBtgRi0+pv+J/o4nB6Ig0TDfrtfL08wvJYzozC7aAncAvqlOvkASrIAXduLnZ7sml 2ePaVVaWiF2IxEoXKclUiMidwNHl7YmWH+g8rL85fSc7Lxmdv8ZeirfXUdNxFfnicJ4T vCbeKEGPNejADWRj7JOTdXPSm6rM/DV/SV92W8mOL7O3LpkzwfkWXfxryc/96ceWuDm+ bY7t7xhhnfE8ZHMKUKn7zS/hCTgyfeMZu2amMFibAdE6tPpItlPby6Ogp4Mapfjd71yn ggFYW5eEFgJlw0FFDTwt8KBdN/v9UYDVFfC8ef7pCdHFEKSgCBU2nYzfynrZCgSt5nvt 2MWQ== X-Gm-Message-State: AOAM531wwwsbxwbHMuh7OiQhg4WrCR+HNTq7kIbBJ3aY2pTOGnKrVg9i QCSGabEoIjoFJ13+X5LK0Yrboy11/bs= X-Google-Smtp-Source: ABdhPJyJ8qzCLLEtne334lGoqyLVM1iQ6ejhjEyaoECvO7Bhf2QT1y4EPZJwTyQRkIcCSyZj7EXIVg== X-Received: by 2002:a05:6402:1e90:: with SMTP id f16mr20698205edf.91.1638982173960; Wed, 08 Dec 2021 08:49:33 -0800 (PST) Received: from skbuf ([188.25.173.50]) by smtp.gmail.com with ESMTPSA id e26sm2364081edr.82.2021.12.08.08.49.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Dec 2021 08:49:33 -0800 (PST) Date: Wed, 8 Dec 2021 18:49:32 +0200 From: Vladimir Oltean To: Marek =?utf-8?B?QmVow7pu?= Cc: Holger Brunck , "netdev@vger.kernel.org" , Jakub Kicinski , Andrew Lunn Subject: Re: [v3 2/2] dsa: mv88e6xxx: make serdes SGMII/Fiber output amplitude configurable Message-ID: <20211208164932.6ojxt64j3v34477k@skbuf> References: <20211207190730.3076-1-holger.brunck@hitachienergy.com> <20211207190730.3076-2-holger.brunck@hitachienergy.com> <20211207202733.56a0cf15@thinkpad> <20211208162852.4d7361af@thinkpad> <20211208171720.6a297011@thinkpad> <20211208172104.75e32a6b@thinkpad> <20211208164131.fy2h652sgyvhm7jx@skbuf> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20211208164131.fy2h652sgyvhm7jx@skbuf> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Dec 08, 2021 at 06:41:31PM +0200, Vladimir Oltean wrote: > On Wed, Dec 08, 2021 at 05:21:04PM +0100, Marek Behún wrote: > > Hello Vladimir, > > > > > but the mv88e6xxx driver also drives switches that allow changing serdes > > > > > modes. There does not need be dedicated TX amplitude register for each serdes > > > > > mode, the point is that we may want to declare different amplitudes for > > > > > different modes. > > > > > > > > > > So the question is: if we go with your binding proposal for the whole mv88e6xxx > > > > > driver, and in the future someone will want to declare different amplitudes for > > > > > different modes on another model, would he need to deprecate your binding or > > > > > would it be easy to extend? > > > > > > > > > > > > > ok I see. So if I follow your proposal in my case it would be something like: > > > > serdes-sgmii-tx-amplitude-millivolt to start with ? > > > > > > > > I can do that. Andrew what do you think? > > > > > > Or maybe two properties: > > > serdes-tx-amplitude-millivolt = <700 1000 1100>; > > > serdes-tx-amplitude-modes = "sgmii", "2500base-x", "10gbase-r"; > > > ? > > > > > > If > > > serdes-tx-amplitude-modes > > > is omitted, then > > > serdes-tx-amplitude-millivolt > > > should only contain one value, and this is used for all serdes modes. > > > > > > This would be compatible with your change. You only need to define the > > > bidning for now, your code can stay the same - you don't need to add > > > support for multiple values or for the second property now, it can be > > > done later when needed. But the binding should be defined to support > > > those different modes. > > > > Vladimir, can you send your thoughts about this proposal? We are trying > > to propose binding for defining serdes TX amplitude. > > I don't have any specific concern here. It sounds reasonable for > different data rates to require different transmitter configurations. > Having separate "serdes-tx-amplitude-millivolt" and "serdes-tx-amplitude-modes" > properties sounds okay, although I think a prefix with "-names" at the > end is more canonical ("pinctrl-names", "clock-names", "reg-names" etc), > so maybe "serdes-tx-amplitude-millivolt-names"? > Maybe we could name the first element "default", and just the others > would be named after a phy-mode. This way, if a specific TX amplitude is > found in the device tree for the currently operating PHY mode, it can be > used, otherwise the default (first) amplitude can be used. Also, maybe drop the "serdes-" prefix? The property will sit under a SERDES lane node, so it would be a bit redundant?