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: 315229 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=-12.7 required=3.0 tests=BAYES_00, 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 0E429C4742C for ; Tue, 3 Nov 2020 09:06:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D061720756 for ; Tue, 3 Nov 2020 09:06:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727923AbgKCJGo (ORCPT ); Tue, 3 Nov 2020 04:06:44 -0500 Received: from foss.arm.com ([217.140.110.172]:44776 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727787AbgKCJGg (ORCPT ); Tue, 3 Nov 2020 04:06:36 -0500 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 Cc: robh+dt@kernel.org, amitk@kernel.org, corbet@lwn.net, daniel.lezcano@linaro.org, lukasz.luba@arm.com, Dietmar.Eggemann@arm.com, morten.rasmussen@arm.com, qperret@google.com, dianders@chromium.org, mka@chromium.org, rnayak@codeaurora.org, rafael@kernel.org, sudeep.holla@arm.com, viresh.kumar@linaro.org, sboyd@kernel.org, nm@ti.com 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> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.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 }