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=-5.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 9B6E8C433F5 for ; Fri, 3 Sep 2021 09:58:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77A406109E for ; Fri, 3 Sep 2021 09:58:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348822AbhICJ7t (ORCPT ); Fri, 3 Sep 2021 05:59:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232273AbhICJ7s (ORCPT ); Fri, 3 Sep 2021 05:59:48 -0400 Received: from mail-lf1-x12c.google.com (mail-lf1-x12c.google.com [IPv6:2a00:1450:4864:20::12c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E70E7C061575; Fri, 3 Sep 2021 02:58:48 -0700 (PDT) Received: by mail-lf1-x12c.google.com with SMTP id c8so10725866lfi.3; Fri, 03 Sep 2021 02:58:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=LXMRkrOMa9GLKEtXyrT+pUgSmaeIa+E2ZbXgDwz3plo=; b=SqmHYtqhoYZZWA59PcoU/x1rQ1id2pS9Sb3t5KzQX+qVfm/0/Qjh00fWYaMa2zyeqx FJ+bH+Cd2HEfF6U/LwxDWxH/F451WfeiaAg/2VIma2Nz6ZTKjZN/6JjQwvTfUgeJwMTr a9NEz3RtNEUKd8hRMksKYjKXdl931mzjg4ZT1Q8bUfwD5npZCazTsyHwLRszfQh6UAOC insRnEGfwv983yBY2xiRx+23mTaZf4pnJSbJerx4uIdz/TACA9ZfTCJPjvPZeg7QvjVb 2rq37l+eH7tOKDwTVJTm33nBlpitgrfcFVs52WmIZyA+3bOFFIirzv8+7EAzTBF671+u h7fw== 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=LXMRkrOMa9GLKEtXyrT+pUgSmaeIa+E2ZbXgDwz3plo=; b=l60z58uwizc3l0pEs5/IAbwzqL0LlpSKhUX7F9bE4UovMDZYgLkiO8lAADJ1Z09+MO ulhRpsz/1dYIYkhcccPD9QT9wyf+gMwSIPFtss4hgkTIa2Q+MY7DXUHg2SslyfDMTMLe sTWyB5v/dtI39+Mr23ZF4UXzL+T5K0v7DoPmdVDK2gBQpWHrfv9vXgEaVxqA6/XnNXs+ USlA7hmjaOOGPm203qS8ZUhSMhXIBTS0VW1DJuBEN7z1XUNO+91dPbYTn1ZjD99XNZ7I 8dzt5A7uD3FYUaiJf5hWE3Q9lxlmrbbvTqifgLeGFJlo0aZESRYjJThPTyb3aAD8E4gq 8HfA== X-Gm-Message-State: AOAM530+9SQCFp6BKC73HgN2Hxn2S6mrylHhgOTdWKDGl93B1TlvxbGG yMXMrJTkWm0e/jU6TBfBofU+YM9otrM= X-Google-Smtp-Source: ABdhPJwhz2eqWOtTgUewpywmxdYJ+44NiMVxCU/u1N50Q6hW0PG8LmncY1jl55ZNZBVa5edjaVtTMw== X-Received: by 2002:a19:4817:: with SMTP id v23mr2247232lfa.154.1630663127152; Fri, 03 Sep 2021 02:58:47 -0700 (PDT) Received: from [192.168.2.145] (46-138-26-37.dynamic.spd-mgts.ru. [46.138.26.37]) by smtp.googlemail.com with ESMTPSA id k8sm530520lja.57.2021.09.03.02.58.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 03 Sep 2021 02:58:46 -0700 (PDT) Subject: Re: [PATCH 1/3] PM: domains: Drop the performance state vote for a device at detach To: Ulf Hansson Cc: "Rafael J . Wysocki" , Viresh Kumar , Linux PM , Dmitry Baryshkov , Jonathan Hunter , Thierry Reding , Rajendra Nayak , Stephan Gerhold , Bjorn Andersson , Linux ARM , Linux Kernel Mailing List References: <20210902101634.827187-1-ulf.hansson@linaro.org> <20210902101634.827187-2-ulf.hansson@linaro.org> <08335cd4-7dc8-3b8b-d63f-374585ffa373@gmail.com> From: Dmitry Osipenko Message-ID: Date: Fri, 3 Sep 2021 12:58:45 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org 03.09.2021 11:22, Ulf Hansson пишет: > On Fri, 3 Sept 2021 at 08:01, Dmitry Osipenko wrote: >> >> 02.09.2021 13:16, Ulf Hansson пишет: >>> When a device is detached from its genpd, genpd loses track of the device, >>> including its performance state vote that may have been requested for it. >>> >>> Rather than relying on the consumer driver to drop the performance state >>> vote for its device, let's do it internally in genpd when the device is >>> getting detached. In this way, we makes sure that the aggregation of the >>> votes in genpd becomes correct. >> >> This is a dangerous behaviour in a case where performance state >> represents voltage. If hardware is kept active on detachment, say it's >> always-on, then it may be a disaster to drop the voltage for the active >> hardware. >> >> It's safe to drop performance state only if you assume that there is a >> firmware behind kernel which has its own layer of performance management >> and it will prevent the disaster by saying 'nope, I'm not doing this'. >> >> The performance state should be persistent for a device and it should be >> controlled in a conjunction with runtime PM. If platform wants to drop >> performance state to zero on detachment, then this behaviour should be >> specific to that platform. > > I understand your concern, but at this point, genpd can't help to fix this. > > Genpd has no information about the device, unless it's attached to it. > For now and for these always on HWs, we simply need to make sure the > device stays attached, in one way or the other. This indeed requires to redesign GENPD to make it more coupled with a device, but this is not a real problem for any of the current API users AFAIK. Ideally the state should be persistent to make API more universal. Since for today we assume that device should be suspended at the time of the detachment (if the default OPP state isn't used), it may be better to add a noisy warning message if pstate!=0, keeping the state untouched if it's not zero. 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[46.138.26.37]) by smtp.googlemail.com with ESMTPSA id k8sm530520lja.57.2021.09.03.02.58.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 03 Sep 2021 02:58:46 -0700 (PDT) Subject: Re: [PATCH 1/3] PM: domains: Drop the performance state vote for a device at detach To: Ulf Hansson Cc: "Rafael J . Wysocki" , Viresh Kumar , Linux PM , Dmitry Baryshkov , Jonathan Hunter , Thierry Reding , Rajendra Nayak , Stephan Gerhold , Bjorn Andersson , Linux ARM , Linux Kernel Mailing List References: <20210902101634.827187-1-ulf.hansson@linaro.org> <20210902101634.827187-2-ulf.hansson@linaro.org> <08335cd4-7dc8-3b8b-d63f-374585ffa373@gmail.com> From: Dmitry Osipenko Message-ID: Date: Fri, 3 Sep 2021 12:58:45 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210903_025852_483281_ACA39DD7 X-CRM114-Status: GOOD ( 23.03 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org MDMuMDkuMjAyMSAxMToyMiwgVWxmIEhhbnNzb24g0L/QuNGI0LXRgjoKPiBPbiBGcmksIDMgU2Vw dCAyMDIxIGF0IDA4OjAxLCBEbWl0cnkgT3NpcGVua28gPGRpZ2V0eEBnbWFpbC5jb20+IHdyb3Rl Ogo+Pgo+PiAwMi4wOS4yMDIxIDEzOjE2LCBVbGYgSGFuc3NvbiDQv9C40YjQtdGCOgo+Pj4gV2hl biBhIGRldmljZSBpcyBkZXRhY2hlZCBmcm9tIGl0cyBnZW5wZCwgZ2VucGQgbG9zZXMgdHJhY2sg b2YgdGhlIGRldmljZSwKPj4+IGluY2x1ZGluZyBpdHMgcGVyZm9ybWFuY2Ugc3RhdGUgdm90ZSB0 aGF0IG1heSBoYXZlIGJlZW4gcmVxdWVzdGVkIGZvciBpdC4KPj4+Cj4+PiBSYXRoZXIgdGhhbiBy ZWx5aW5nIG9uIHRoZSBjb25zdW1lciBkcml2ZXIgdG8gZHJvcCB0aGUgcGVyZm9ybWFuY2Ugc3Rh dGUKPj4+IHZvdGUgZm9yIGl0cyBkZXZpY2UsIGxldCdzIGRvIGl0IGludGVybmFsbHkgaW4gZ2Vu cGQgd2hlbiB0aGUgZGV2aWNlIGlzCj4+PiBnZXR0aW5nIGRldGFjaGVkLiBJbiB0aGlzIHdheSwg d2UgbWFrZXMgc3VyZSB0aGF0IHRoZSBhZ2dyZWdhdGlvbiBvZiB0aGUKPj4+IHZvdGVzIGluIGdl bnBkIGJlY29tZXMgY29ycmVjdC4KPj4KPj4gVGhpcyBpcyBhIGRhbmdlcm91cyBiZWhhdmlvdXIg aW4gYSBjYXNlIHdoZXJlIHBlcmZvcm1hbmNlIHN0YXRlCj4+IHJlcHJlc2VudHMgdm9sdGFnZS4g SWYgaGFyZHdhcmUgaXMga2VwdCBhY3RpdmUgb24gZGV0YWNobWVudCwgc2F5IGl0J3MKPj4gYWx3 YXlzLW9uLCB0aGVuIGl0IG1heSBiZSBhIGRpc2FzdGVyIHRvIGRyb3AgdGhlIHZvbHRhZ2UgZm9y IHRoZSBhY3RpdmUKPj4gaGFyZHdhcmUuCj4+Cj4+IEl0J3Mgc2FmZSB0byBkcm9wIHBlcmZvcm1h bmNlIHN0YXRlIG9ubHkgaWYgeW91IGFzc3VtZSB0aGF0IHRoZXJlIGlzIGEKPj4gZmlybXdhcmUg YmVoaW5kIGtlcm5lbCB3aGljaCBoYXMgaXRzIG93biBsYXllciBvZiBwZXJmb3JtYW5jZSBtYW5h Z2VtZW50Cj4+IGFuZCBpdCB3aWxsIHByZXZlbnQgdGhlIGRpc2FzdGVyIGJ5IHNheWluZyAnbm9w ZSwgSSdtIG5vdCBkb2luZyB0aGlzJy4KPj4KPj4gVGhlIHBlcmZvcm1hbmNlIHN0YXRlIHNob3Vs ZCBiZSBwZXJzaXN0ZW50IGZvciBhIGRldmljZSBhbmQgaXQgc2hvdWxkIGJlCj4+IGNvbnRyb2xs ZWQgaW4gYSBjb25qdW5jdGlvbiB3aXRoIHJ1bnRpbWUgUE0uIElmIHBsYXRmb3JtIHdhbnRzIHRv IGRyb3AKPj4gcGVyZm9ybWFuY2Ugc3RhdGUgdG8gemVybyBvbiBkZXRhY2htZW50LCB0aGVuIHRo aXMgYmVoYXZpb3VyIHNob3VsZCBiZQo+PiBzcGVjaWZpYyB0byB0aGF0IHBsYXRmb3JtLgo+IAo+ IEkgdW5kZXJzdGFuZCB5b3VyIGNvbmNlcm4sIGJ1dCBhdCB0aGlzIHBvaW50LCBnZW5wZCBjYW4n dCBoZWxwIHRvIGZpeCB0aGlzLgo+IAo+IEdlbnBkIGhhcyBubyBpbmZvcm1hdGlvbiBhYm91dCB0 aGUgZGV2aWNlLCB1bmxlc3MgaXQncyBhdHRhY2hlZCB0byBpdC4KPiBGb3Igbm93IGFuZCBmb3Ig dGhlc2UgYWx3YXlzIG9uIEhXcywgd2Ugc2ltcGx5IG5lZWQgdG8gbWFrZSBzdXJlIHRoZQo+IGRl dmljZSBzdGF5cyBhdHRhY2hlZCwgaW4gb25lIHdheSBvciB0aGUgb3RoZXIuCgpUaGlzIGluZGVl ZCByZXF1aXJlcyB0byByZWRlc2lnbiBHRU5QRCB0byBtYWtlIGl0IG1vcmUgY291cGxlZCB3aXRo IGEKZGV2aWNlLCBidXQgdGhpcyBpcyBub3QgYSByZWFsIHByb2JsZW0gZm9yIGFueSBvZiB0aGUg Y3VycmVudCBBUEkgdXNlcnMKQUZBSUsuIElkZWFsbHkgdGhlIHN0YXRlIHNob3VsZCBiZSBwZXJz aXN0ZW50IHRvIG1ha2UgQVBJIG1vcmUgdW5pdmVyc2FsLgoKU2luY2UgZm9yIHRvZGF5IHdlIGFz c3VtZSB0aGF0IGRldmljZSBzaG91bGQgYmUgc3VzcGVuZGVkIGF0IHRoZSB0aW1lIG9mCnRoZSBk ZXRhY2htZW50IChpZiB0aGUgZGVmYXVsdCBPUFAgc3RhdGUgaXNuJ3QgdXNlZCksIGl0IG1heSBi ZSBiZXR0ZXIKdG8gYWRkIGEgbm9pc3kgd2FybmluZyBtZXNzYWdlIGlmIHBzdGF0ZSE9MCwga2Vl cGluZyB0aGUgc3RhdGUgdW50b3VjaGVkCmlmIGl0J3Mgbm90IHplcm8uCgpfX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpsaW51eC1hcm0ta2VybmVsIG1haWxp bmcgbGlzdApsaW51eC1hcm0ta2VybmVsQGxpc3RzLmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3Rz LmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5mby9saW51eC1hcm0ta2VybmVsCg==