From patchwork Tue Nov 3 09:06:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 11876363 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 92C41C2D0A3 for ; Tue, 3 Nov 2020 09:08:03 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 11BEF20756 for ; Tue, 3 Nov 2020 09:08:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="BLo66MAx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 11BEF20756 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:MIME-Version:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:References:In-Reply-To:Message-Id:Date:Subject:To: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ezf6H0JZQQ2BuQzqCzZqbUYKQ7nR9V/x8GzR/WsREMM=; b=BLo66MAxvwVV2nVs0WMKvhjHfu msp9oCrv4PvPQNtQq4mVPZmHbDTnhGTAhL2CR+hQ01r3HoujJ0869tVMNDG/KIOvoFk9yGeV2Z27+ JrnxUDypYCBkIZ+xaDdoOYAYaog9jK2mYeJ43iFV8/z0BBu/SaQ4PwACzlYEtvFV3zLQRG32l7lA0 n3voP2b6KhZqekPWHCzYX9x09hFG1zHezoL2qnPkp9SOcA6kdlZmjJVd1+KK6k8Ddi97SFc/Gidz3 5F74rwejY9rATqRS76Cj6qsG1KpxyhvQYzVkHqjJKQgWPO5NkTMlzQVHcxVMrJiWff3mGMasF2Xju GqsjoCkg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kZsHf-0002LT-Os; Tue, 03 Nov 2020 09:07:21 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kZsGy-00024k-SG for linux-arm-kernel@lists.infradead.org; Tue, 03 Nov 2020 09:06:38 +0000 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 CAFCB139F; Tue, 3 Nov 2020 01:06:35 -0800 (PST) Received: from e123648.arm.com (unknown [10.57.19.30]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 409B03F719; Tue, 3 Nov 2020 01:06:31 -0800 (PST) From: Lukasz Luba To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-doc@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v4 4/4] docs: power: Update Energy Model with new flag indicating power scale Date: Tue, 3 Nov 2020 09:06:00 +0000 Message-Id: <20201103090600.29053-5-lukasz.luba@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201103090600.29053-1-lukasz.luba@arm.com> References: <20201103090600.29053-1-lukasz.luba@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201103_040637_108790_42DB3589 X-CRM114-Status: GOOD ( 13.28 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: nm@ti.com, rafael@kernel.org, daniel.lezcano@linaro.org, rnayak@codeaurora.org, corbet@lwn.net, sboyd@kernel.org, viresh.kumar@linaro.org, mka@chromium.org, amitk@kernel.org, dianders@chromium.org, morten.rasmussen@arm.com, robh+dt@kernel.org, sudeep.holla@arm.com, qperret@google.com, Dietmar.Eggemann@arm.com, lukasz.luba@arm.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Update description and meaning of a new flag, which indicates the type of power scale used for a registered Energy Model (EM) device. Reviewed-by: Quentin Perret Signed-off-by: Lukasz Luba --- Documentation/power/energy-model.rst | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/Documentation/power/energy-model.rst b/Documentation/power/energy-model.rst index ba7aa581b307..60ac091d3b0d 100644 --- a/Documentation/power/energy-model.rst +++ b/Documentation/power/energy-model.rst @@ -30,6 +30,8 @@ These subsystems are more interested in estimation of power used in the past, thus the real milli-Watts might be needed. An example of these requirements can be found in the Intelligent Power Allocation in Documentation/driver-api/thermal/power_allocator.rst. +Kernel subsystems might implement automatic detection to check whether EM +registered devices have inconsistent scale (based on EM internal flag). Important thing to keep in mind is that when the power values are expressed in an 'abstract scale' deriving real energy in milli-Joules would not be possible. @@ -86,7 +88,7 @@ Drivers are expected to register performance domains into the EM framework by calling the following API:: int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, - struct em_data_callback *cb, cpumask_t *cpus); + struct em_data_callback *cb, cpumask_t *cpus, bool milliwatts); Drivers must provide a callback function returning tuples for each performance state. The callback function provided by the driver is free @@ -94,6 +96,10 @@ to fetch data from any relevant location (DT, firmware, ...), and by any mean deemed necessary. Only for CPU devices, drivers must specify the CPUs of the performance domains using cpumask. For other devices than CPUs the last argument must be set to NULL. +The last argument 'milliwatts' is important to set with correct value. Kernel +subsystems which use EM might rely on this flag to check if all EM devices use +the same scale. If there are different scales, these subsystems might decide +to: return warning/error, stop working or panic. See Section 3. for an example of driver implementing this callback, and kernel/power/energy_model.c for further documentation on this API. @@ -169,7 +175,8 @@ EM framework:: 37 nr_opp = foo_get_nr_opp(policy); 38 39 /* And register the new performance domain */ - 40 em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus); - 41 - 42 return 0; - 43 } + 40 em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus, + 41 true); + 42 + 43 return 0; + 44 }