From patchwork Mon Mar 21 09:57:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 553423 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6B2BC433EF for ; Mon, 21 Mar 2022 09:58:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346106AbiCUJ7k (ORCPT ); Mon, 21 Mar 2022 05:59:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346153AbiCUJ7h (ORCPT ); Mon, 21 Mar 2022 05:59:37 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4E96B25E90; Mon, 21 Mar 2022 02:58:06 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 10FD4106F; Mon, 21 Mar 2022 02:58:06 -0700 (PDT) Received: from e123648.arm.com (unknown [10.57.22.222]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 351C33F766; Mon, 21 Mar 2022 02:58:03 -0700 (PDT) From: Lukasz Luba To: linux-kernel@vger.kernel.org Cc: lukasz.luba@arm.com, dietmar.eggemann@arm.com, Pierre.Gondois@arm.com, ionela.voinescu@arm.com, viresh.kumar@linaro.org, rafael@kernel.org, daniel.lezcano@linaro.org, linux-pm@vger.kernel.org, mka@chromium.org, nm@ti.com, sboyd@kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, cristian.marussi@arm.com, sudeep.holla@arm.com, matthias.bgg@gmail.com Subject: [RESEND][PATCH 6/8] Documentation: EM: Add artificial EM registration description Date: Mon, 21 Mar 2022 09:57:27 +0000 Message-Id: <20220321095729.20655-7-lukasz.luba@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220321095729.20655-1-lukasz.luba@arm.com> References: <20220321095729.20655-1-lukasz.luba@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Add description about new artificial EM registration and use cases. Update also the documentation with the new .get_cost() callback description and usage. Signed-off-by: Lukasz Luba Reviewed-by: Ionela Voinescu --- Documentation/power/energy-model.rst | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/power/energy-model.rst b/Documentation/power/energy-model.rst index fd29ed2506c0..feb257b7f350 100644 --- a/Documentation/power/energy-model.rst +++ b/Documentation/power/energy-model.rst @@ -123,6 +123,26 @@ allows a platform to register EM power values which are reflecting total power (static + dynamic). These power values might be coming directly from experiments and measurements. +Registration of 'artificial' EM +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +There is an option to provide a custom callback for drivers missing detailed +knowledge about power value for each performance state. The callback +.get_cost() is optional and provides the 'cost' values used by the EAS. +This is useful for platforms that only provide information on relative +efficiency between CPU types, where one could use the information to +create an abstract power model. But even an abstract power model can +sometimes be hard to fit in, given the input power value size restrictions. +The .get_cost() allows to provide the 'cost' values which reflect the +efficiency of the CPUs. This would allow to provide EAS information which +has different relation than what would be forced by the EM internal +formulas calculating 'cost' values. To register an EM for such platform, the +driver must set the flag 'milliwatts' to 0, provide .get_power() callback +and provide .get_cost() callback. The EM framework would handle such platform +properly during registration. A flag EM_PERF_DOMAIN_ARTIFICIAL is set for such +platform. Special care should be taken by other frameworks which are using EM +to test and treat this flag properly. + Registration of 'simple' EM ~~~~~~~~~~~~~~~~~~~~~~~~~~~