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=-4.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED autolearn=ham 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 D5F30C43381 for ; Mon, 1 Apr 2019 08:40:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9AD7C2086C for ; Mon, 1 Apr 2019 08:40:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=baylibre-com.20150623.gappssmtp.com header.i=@baylibre-com.20150623.gappssmtp.com header.b="m6EHyBNn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728624AbfDAIkZ (ORCPT ); Mon, 1 Apr 2019 04:40:25 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:39997 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728012AbfDAIkY (ORCPT ); Mon, 1 Apr 2019 04:40:24 -0400 Received: by mail-wm1-f65.google.com with SMTP id z24so10359606wmi.5 for ; Mon, 01 Apr 2019 01:40:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20150623.gappssmtp.com; s=20150623; h=message-id:subject:from:to:cc:date:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=SP6dtRR4XnBdiX6pYVY4GbOIbGYL0lpRYejuQl03xJ8=; b=m6EHyBNnSSUkYUtR23/XjZmIic9axelIbgMEk7IPl1hIbkV9FQZ/yRv+ujdwe64VXV NWvSW+OkMcwo+RgYHZkX6fdW9Dwq+P9opHQPelu/0G1OSXQYow+9Iss4nE9YdjSQh/Hj dGgPbqUOVarFCKsC8as7jsb10XVg79B4AN+r+Hc35/pzX/7aIS7RKL2PasM2YWotg0Ag m2kV5xsWsJ/v1Pjxk57uFur8CQAqK+EsZJNM5zYg6Hp9l80wCol+FclIM0YepAK0S/Ua aeEkLxmNTUTZ7seOujwOjmQQxWO1W2xhlJ0h7HdrZzHWHMT8iu6uiLbtiOXyENy7pn+A YJ6w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=SP6dtRR4XnBdiX6pYVY4GbOIbGYL0lpRYejuQl03xJ8=; b=rkwn8ajEixGS6XWphikid+zzzAga8feJU0i0SATSmvN2bc2g+sGj90d7b6Gd4sb4nk kBB/wMYQ61nDr5DTamggZRvDDh6Y937JDz0iLGbH+kXVL1bihOicYye5dR2Ezcl9dz0u g4yWWW0dCN2fM0prFqT0Rdq5nPUromxlY7ykJ7R5rQiRYAOtuvYdgZLmXgnFMhrQI5CS 9ex/aalErALKE8jw6lza7caxuF3vrPZJfExP58Qa77OOaMFkxMq094KorR/Qy4GPyi1j 2+qT3WX2iruxqnlMl8I3XBZj0RnN3xjGZu/UUlDXbWfq80Ex590wZkoyaqDdE44/ThvN DJ+w== X-Gm-Message-State: APjAAAVoCVY645PnzoIQgUjwmOx1pLv1T8jDgpr7gpGw7X0Pgc4yCatC mrKXrljBijHM/HN+B2ujG4gsNg== X-Google-Smtp-Source: APXvYqzftgbkDH5aDIC8sGZWKMCqOeiwTPMCcCUD4KUuV+cSOmuE4MG/C9OqHLfULsPow1H1Ple08w== X-Received: by 2002:a7b:c769:: with SMTP id x9mr11364300wmk.103.1554108023014; Mon, 01 Apr 2019 01:40:23 -0700 (PDT) Received: from boomer.baylibre.com ([2a01:e34:eeb6:4690:106b:bae3:31ed:7561]) by smtp.gmail.com with ESMTPSA id q17sm7746726wrw.70.2019.04.01.01.40.21 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 01 Apr 2019 01:40:22 -0700 (PDT) Message-ID: <63fc525faf2d82cb2436a17ab2206293aeef6c31.camel@baylibre.com> Subject: Re: [PATCH 1/3] clk: meson: mpll: properly handle spread spectrum From: Jerome Brunet To: Martin Blumenstingl Cc: Neil Armstrong , linux-amlogic@lists.infradead.org, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 01 Apr 2019 10:40:20 +0200 In-Reply-To: References: <20190329153325.23869-1-jbrunet@baylibre.com> <20190329153325.23869-2-jbrunet@baylibre.com> <3bef1bb26e9eff0cfc20cd4bb78a5d7cea4c5076.camel@baylibre.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2019-03-30 at 16:56 +0100, Martin Blumenstingl wrote: > Hi Jerome, > > On Sat, Mar 30, 2019 at 12:07 AM Jerome Brunet wrote: > > On Fri, 2019-03-29 at 20:39 +0100, Martin Blumenstingl wrote: > > > Hi Jerome, > > > > > > On Fri, Mar 29, 2019 at 4:34 PM Jerome Brunet wrote: > > > > The bit 'SSEN' available on some MPLL DSS outputs is not related to the > > > > fractional part of the divider but to the function called > > > > 'Spread Spectrum'. > > > > > > > > This function might be used to solve EM issues by adding a jitter on > > > > clock signal. This widens the signal spectrum and weakens the peaks in it. > > > > > > > > While spread spectrum might be useful for some application, it is > > > > problematic for others, such as audio. > > > > > > > > This patch introduce a new flag to the MPLL driver to enable (or not) the > > > > spread spectrum function. > > > > > > > > Fixes: 1f737ffa13ef ("clk: meson: mpll: fix mpll0 fractional part ignored") > > > > Signed-off-by: Jerome Brunet > > > > --- > > > > drivers/clk/meson/clk-mpll.c | 9 ++++++--- > > > > drivers/clk/meson/clk-mpll.h | 1 + > > > > 2 files changed, 7 insertions(+), 3 deletions(-) > > > > [...] > > > > Yes, none of our application require spread spectrum > thank you for the explanation. can you please add it to the patch description? I think I described spread spectrum already in the commit description. > > > The fact is that only 2 MPLL had this bit, mpll0 on gx (without effect) and > > mpll0 on axg: actually spread spectrum impacts mpll2, making it unusable, as > > explained in the related patch > > > > > based on the original commit 1f737ffa13ef ("clk: meson: mpll: fix > > > mpll0 fractional part ignored") it seems that > > > CLK_MESON_MPLL_SPREAD_SPECTRUM should be set for mpll0 (at least on > > > GXBB and Meson8b) > > > > > > > There a patch specifically targeting gxbb. > I missed that, sorry for the noise > > > I have checked on GXL and this bit had no effect (fractional part still on, no > > spread spectrum) > > > > So either we fixed something since then or I messed up when doing the patch > > initially. > > > > Feel free to cross check > I tried it on Meson8b and it seems that there's no difference. I've > done a bit of software archaeology: > $ grep -R mpll_cntl uboot-2015-01-15-23a3562521/ | grep "=" | head -n3 > uboot-2015-01-15-23a3562521/board/amlogic/m8_k100_1G/firmware/timming.c: > .mpll_cntl = 0x600009A9, //2.5G, fixed > uboot-2015-01-15-23a3562521/board/amlogic/m8_k100_2G/firmware/timming.c: > .mpll_cntl = 0x600009A9, //2.5G, fixed > uboot-2015-01-15-23a3562521/board/amlogic/m8b_ft_v1/firmware/timming.c: > .mpll_cntl = 0x600009A9, //2.5G, fixed > > Ethernet is still working on my Odroid-C1, so you can add my: > Tested-by: Martin Blumenstingl > > > Regards > Martin