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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 B48A8C433DB for ; Fri, 19 Feb 2021 04:59:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B71464EB8 for ; Fri, 19 Feb 2021 04:59:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229652AbhBSE7L (ORCPT ); Thu, 18 Feb 2021 23:59:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229544AbhBSE7G (ORCPT ); Thu, 18 Feb 2021 23:59:06 -0500 Received: from mail-pg1-x529.google.com (mail-pg1-x529.google.com [IPv6:2607:f8b0:4864:20::529]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9CD23C061756 for ; Thu, 18 Feb 2021 20:58:26 -0800 (PST) Received: by mail-pg1-x529.google.com with SMTP id t11so2805214pgu.8 for ; Thu, 18 Feb 2021 20:58:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=VQ8JfAUf/ySg/ATklOLfVi6FRg+WrMTayYjOprp1Sx0=; b=zrt/i2IK+MNx8nousJ5vhUkJhPOg+W4lAaza3KU7WU5akL9GwRYl6fQtYhNv5OPgY+ DH+LAVbb4FtDeXzzY815wVASFyQv3PCGNAStQH0V4uw8EBNU1Ir8Hsl/6tzswvd1TC8c cU0qPNlAxe9fwZ4gRAFODY1w66JGzR3S+RYHoonlLtQt9BbnkLkdx8RBgxU2LTn/utZb /YDLg1RG0yahHSXebbwpRlOJdhqjI14F0xjzasUbv7hvqKPJm2vwlVBm6T1JMwWWT2N9 NkJkVQb6OtohZ1RPApNY6L7wwiT0oR+nP9JDUape8vht0cXFLole/ud9E1+fq/+LyGZP fUgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=VQ8JfAUf/ySg/ATklOLfVi6FRg+WrMTayYjOprp1Sx0=; b=swBT+tzo7gsAv0k4y6WblPLs4ErMZEpJJP7Tb4TXC26nifciHQAv1Kii0est+4KgX3 U73rwOV/QVLkFP5V7iEN+7MkPeKJ998M1l9W7nsqau5bjfk4lRbWSv3DmTYayLhS3dUg LvRE0X13AbsCToCFfAml5hbaK1Mew7qnupzD57WDRcuYj2r5tg1pwZURajfG1AZoyRQB 6ZdaO1JBI4EmJ7PI7Ufrukh4FKpNELmiuRzT4y3KIihvjjkbAqaIiYbECQ/GnGuYfCJE qFwD4FL+l7p+0uVj7lmCxuptcFv3nCfyY7vgzsLYgGk56v8YbHAJRI0qvL+MY7fWX65E CBTQ== X-Gm-Message-State: AOAM5316wnrGwhghV3U+5AvzglSl2oZv0J3Ag7Zur8BgVzX3XTsd3Gef gZl/Vq9QJzE8PpXru3YPZjmlqg== X-Google-Smtp-Source: ABdhPJwu4+l3z0J6l2dIbzGBCfMCuNcRbcfi8xlFg/zWmBVxwfBMR2E2oxOYuMXfJN2cC8DQBRZXAg== X-Received: by 2002:a63:1845:: with SMTP id 5mr7015563pgy.244.1613710706075; Thu, 18 Feb 2021 20:58:26 -0800 (PST) Received: from localhost ([122.172.59.240]) by smtp.gmail.com with ESMTPSA id s18sm7433890pfm.129.2021.02.18.20.58.25 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Feb 2021 20:58:25 -0800 (PST) Date: Fri, 19 Feb 2021 10:28:23 +0530 From: Viresh Kumar To: Ionela Voinescu Cc: Rafael Wysocki , Catalin Marinas , Will Deacon , Vincent Guittot , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, Sudeep Holla , Greg Kroah-Hartman Subject: Re: [PATCH V3 1/2] topology: Allow multiple entities to provide sched_freq_tick() callback Message-ID: <20210219045823.beeijwaymd63prk7@vireshk-i7> References: <20210203114521.GA6380@arm.com> <20210205091424.3od3tme3f7mh7ebp@vireshk-i7> <20210217002422.GA17422@arm.com> <20210218093304.3mt3o7kbeymn5ofl@vireshk-i7> <20210218163635.GA23622@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210218163635.GA23622@arm.com> User-Agent: NeoMutt/20180716-391-311a52 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18-02-21, 16:36, Ionela Voinescu wrote: > Yes, we don't care if there is no cpufreq driver, as the use of AMUs won't > get initialised either. But we do care if there is a cpufreq driver that > does not support frequency invariance, which is the example above. > > The intention with the patches that made cpufreq based invariance generic > a while back was for it to be present, seamlessly, for as many drivers as > possible, as a less than accurate invariance default method is still > better than nothing. Right. > So only a few drivers today don't support cpufreq based FI Only two AFAICT, both x86, and the AMU stuff doesn't conflict with them. drivers/cpufreq/intel_pstate.c drivers/cpufreq/longrun.c > but it's not a guarantee that it will stay this way. What do you mean by "no guarantee" here ? The very core routines (cpufreq_freq_transition_end() and cpufreq_driver_fast_switch()) of the cpufreq core call arch_set_freq_scale() today and this isn't going to change anytime soon. If something gets changed there someone will need to see other parts of the kernel which may get broken with that. I don't see any need of complicating other parts of the kernel like, amu or cppc code for that. They should be kept simple and they should assume cpufreq invariance will be supported as it is today. -- viresh