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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 C3D1CC433E7 for ; Thu, 3 Sep 2020 07:13:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 91A0A2071B for ; Thu, 3 Sep 2020 07:13:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="rG41yKIj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727943AbgICHNp (ORCPT ); Thu, 3 Sep 2020 03:13:45 -0400 Received: from mail29.static.mailgun.info ([104.130.122.29]:19913 "EHLO mail29.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726686AbgICHNo (ORCPT ); Thu, 3 Sep 2020 03:13:44 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1599117223; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=4z34Z3fn8MgWcmuiduYWqSNTgBUNPiswOSFypKcoKAo=; b=rG41yKIjNj9veZxjdrK8ryteNWXNNDsmZGOy52+LdG8yHq9Uq8PZmLXetnixVCVCXBvWudTu /IFxLYxbt0YVfW18z/dKYWySa+9o+B7QAN+psw/gCwcwV+kiqeZNtpU1XqXfEuVwc2bibGW4 bhx+pI9kdD2m69PpjT6yN2QRFXg= X-Mailgun-Sending-Ip: 104.130.122.29 X-Mailgun-Sid: WyI1YmJiNiIsICJkZXZpY2V0cmVlQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n04.prod.us-west-2.postgun.com with SMTP id 5f5097999bdf68cc036d7acd (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Thu, 03 Sep 2020 07:13:29 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 11D5DC433C9; Thu, 3 Sep 2020 07:13:29 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: sibis) by smtp.codeaurora.org (Postfix) with ESMTPSA id 19B63C433C6; Thu, 3 Sep 2020 07:13:27 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 03 Sep 2020 12:43:27 +0530 From: Sibi Sankar To: Viresh Kumar Cc: ansuelsmth@gmail.com, vincent.guittot@linaro.org, saravanak@google.com, 'Sudeep Holla' , "'Rafael J. Wysocki'" , 'Rob Herring' , linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: R: [RFC PATCH v3 0/2] Add Krait Cache Scaling support In-Reply-To: <20200903065314.y3ynhwydahaeg6o6@vireshk-i7> References: <20200821140026.19643-1-ansuelsmth@gmail.com> <20200824104053.kpjpwzl2iw3lpg2m@vireshk-i7> <039d01d67f6a$188700d0$49950270$@gmail.com> <20200903065314.y3ynhwydahaeg6o6@vireshk-i7> Message-ID: <6dc62d231c776b2cdfdc36cfe36e4140@codeaurora.org> X-Sender: sibis@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 2020-09-03 12:23, Viresh Kumar wrote: > On 31-08-20, 09:41, ansuelsmth@gmail.com wrote: >> On 31-08-20, Sibi wrote: >> > On 2020-08-24 16:10, Viresh Kumar wrote: >> > > +Vincent/Saravana/Sibi >> > > >> > > On 21-08-20, 16:00, Ansuel Smith wrote: >> > >> This adds Krait Cache scaling support using the cpufreq notifier. >> > >> I have some doubt about where this should be actually placed (clk or >> > >> cpufreq)? >> > >> Also the original idea was to create a dedicated cpufreq driver (like >> > >> it's done in >> > >> the codeaurora qcom repo) by copying the cpufreq-dt driver and adding >> > >> the cache >> > >> scaling logic but i still don't know what is better. Have a very >> > >> similar driver or >> > >> add a dedicated driver only for the cache using the cpufreq notifier >> > >> and do the >> > >> scale on every freq transition. >> > >> Thanks to everyone who will review or answer these questions. >> > > >> > > Saravana was doing something with devfreq to solve such issues if I >> > > wasn't mistaken. >> > > >> > > Sibi ? >> > >> > IIRC the final plan was to create a devfreq device >> > and devfreq-cpufreq based governor to scale them, this >> > way one can switch to a different governor if required. >> >> So in this case I should convert this patch to a devfreq driver- > > I think this should happen nevertheless. You are doing DVFS for a > device which isn't a CPU and devfreq looks to be the right place of > doing so. > >> Isn't overkill to use a governor for such a task? >> (3 range based on the cpufreq?) > > I am not sure about the governor part here, maybe it won't be required > ? Yeah I don't see it being needed in ^^ case as well. I just mentioned them as an advantage in case you wanted to switch to a different governor in the future. https://lore.kernel.org/lkml/d0bc8877-6d41-f54e-1c4c-2fadbb9dcd0b@samsung.com/ A devfreq governor tracking cpufreq was generally accepted but using a cpufreq notifier to achieve that was discouraged. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.