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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 0D124C6786F for ; Sun, 28 Oct 2018 12:58:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AEB6F20843 for ; Sun, 28 Oct 2018 12:58:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="nltJ8sQe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AEB6F20843 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727623AbeJ1Vnb (ORCPT ); Sun, 28 Oct 2018 17:43:31 -0400 Received: from mail-lj1-f193.google.com ([209.85.208.193]:36376 "EHLO mail-lj1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727150AbeJ1Vnb (ORCPT ); Sun, 28 Oct 2018 17:43:31 -0400 Received: by mail-lj1-f193.google.com with SMTP id s15-v6so5224872lji.3; Sun, 28 Oct 2018 05:58:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=xYy1WKAbtC+bLTvu93oFushNxSY5ujZsJKK45wvq15s=; b=nltJ8sQe7yey0wtncJiJiNW5puOcK9q7NVUX5evo5AMUL8W+GKdEibpllA5a4pXXtz SgYZ10+vYAwQQla5dpkd8nH1xVQrO6KvV21SWGWativixq+3vxWHoK0vyfaY8AkpS/p7 nnbTp2B6hafke53YhdVWuRR5Jx9FzuSIlXDmVK/nRWi9llEKAfx2kfuoHY7LgVogbmfw 8RuUsf8jvAqHjgvq2mdzQRVePkJuR0tU55aYkCHVdf4cdYVOPfA8lfVofRn6y3JeALkw gbktmu91qAflEYUb+bxN79dZQEAdMI4buKmUx/KXlMaeimvsPqE/Idq3nTSX+bthVilA fa4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=xYy1WKAbtC+bLTvu93oFushNxSY5ujZsJKK45wvq15s=; b=lncpAu0MsmotO2u+cewAkRSkVdhH5yP+7882eRzH4cmA1+DxcmOtjX672FX3vq7mrQ V6t4NMeedoMJVDUM32PLdzcbuS3bILZPkE7wJE5keUyVUP5PcT9fTeJjpJWJn8OwdqZm C22FZExzFdB7/wJndl9XEqhVHnKC05DSNQnLsEqWgC85VZQXufcOhcaWo7AXJDzoPzNK Q8jICdXchzI/S5wP4yeQVYLXjqmw82uQorrq5Tna0Az8ZCUygACK4law3D39cuN8xTKz OhyaO39mGpDwgfDA09Czi/y+gSdVrrawcXaC95bWheyRA6/ALkfZiMcxXfJJ1Y7i8R8u T/hw== X-Gm-Message-State: AGRZ1gItwvrXzXIwt/PDwK5aUsmFDEjYFuIPsrir1VXpWpw4m6cqWK1J 819yK6SNvJTN9KTDsPmj8UKpjxmo X-Google-Smtp-Source: AJdET5dIg/B5YEbwi7EPHVU3s8AwgB/8ki7yRWdC8g3Uz8bOaVtojfjHgnzuQ0HP83N3+L9oUcxW9w== X-Received: by 2002:a2e:8596:: with SMTP id b22-v6mr4616463lji.122.1540731533898; Sun, 28 Oct 2018 05:58:53 -0700 (PDT) Received: from [192.168.2.145] ([109.252.91.118]) by smtp.googlemail.com with ESMTPSA id p63-v6sm2686093lfg.46.2018.10.28.05.58.52 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 28 Oct 2018 05:58:53 -0700 (PDT) Subject: Re: [RFC PATCH v2 01/17] OPP: Allow to request stub voltage regulators To: Lucas Stach , Viresh Kumar Cc: "Rafael J. Wysocki" , Rob Herring , Thierry Reding , Jonathan Hunter , Nishanth Menon , Stephen Boyd , Marcel Ziswiler , linux-tegra@vger.kernel.org, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20181021205501.23943-1-digetx@gmail.com> <20181021205501.23943-2-digetx@gmail.com> <20181022053636.ag62j3rj3vovbz53@vireshk-i7> <20181022113224.b5fiebgy2aap66nd@vireshk-i7> <29f893be-feed-c4c5-8468-51f7228dd468@gmail.com> <20181024064123.lbpbeervghp35fe7@vireshk-i7> <1540568255.2245.11.camel@pengutronix.de> From: Dmitry Osipenko Message-ID: Date: Sun, 28 Oct 2018 15:58:25 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <1540568255.2245.11.camel@pengutronix.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/26/18 6:37 PM, Lucas Stach wrote: > Am Freitag, den 26.10.2018, 15:03 +0300 schrieb Dmitry Osipenko: > [...] >>> On the other hand, the tegra20 cpufreq driver is common across a lot of boards. >>> What will happen if the DT for some of the boards isn't correct and missed the >>> necessary regulator node ? >> >> AFAIK, there is assumption that bootloader should setup regulators in >> a way that kernel could work properly at max clock rates. Otherwise >> things won't work. > > This isn't true. The assumption is that the bootloader sets up the > regulators such that stable operation at the CPU speed used by the > bootloader is guaranteed. > > Often the bootloader doesn't know about specific SKUs, so drives things > at a rate/voltage that is safe across all SKUs [1], in which case the > bootloader is totally unaware of the voltage needed to run the CPU at > highest possible clock frequency. > > Regards, > Lucas > > [1] http://git.denx.de/?p=u-boot.git;a=commit;h=2364e151e432b4ccf32dc9e6147121253d4ff86d > Oh, okay. Thank you for pointing at [1], though the assumption is true for T20. I agree that it's better not to rely on configuration left from bootloader in general.