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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92675C77B7A for ; Tue, 30 May 2023 09:32:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229681AbjE3Jcg (ORCPT ); Tue, 30 May 2023 05:32:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230349AbjE3JcN (ORCPT ); Tue, 30 May 2023 05:32:13 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 25450135; Tue, 30 May 2023 02:31:38 -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 34EF02F4; Tue, 30 May 2023 02:32:23 -0700 (PDT) Received: from [192.168.178.6] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B01563F663; Tue, 30 May 2023 02:31:35 -0700 (PDT) Message-ID: <70e630b8-e577-a148-0179-61aedf910c09@arm.com> Date: Tue, 30 May 2023 11:31:34 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v2 06/17] PM: EM: Add update_power() callback for runtime modifications Content-Language: en-US To: Lukasz Luba , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rafael@kernel.org Cc: rui.zhang@intel.com, amit.kucheria@verdurent.com, amit.kachhap@gmail.com, daniel.lezcano@linaro.org, viresh.kumar@linaro.org, len.brown@intel.com, pavel@ucw.cz, Pierre.Gondois@arm.com, ionela.voinescu@arm.com, rostedt@goodmis.org, mhiramat@kernel.org References: <20230512095743.3393563-1-lukasz.luba@arm.com> <20230512095743.3393563-7-lukasz.luba@arm.com> From: Dietmar Eggemann In-Reply-To: <20230512095743.3393563-7-lukasz.luba@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/05/2023 11:57, Lukasz Luba wrote: > The Energy Model (EM) is going to support runtime modifications. This > new callback would be used in the upcoming EM changes. The drivers > or frameworks which want to modify the EM have to implement the > update_power() callback and provide it via EM API > em_dev_update_perf_domain(). The callback is then used by the EM > framework to get new power values for each frequency in existing EM. Do we have any numbers or feedback that the chosen design (i.e. update per performance state through update_power()) is performant enough for the anticipated use case on real devices? > Signed-off-by: Lukasz Luba > --- > include/linux/energy_model.h | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h > index 8069f526c9d8..cc2bf607191e 100644 > --- a/include/linux/energy_model.h > +++ b/include/linux/energy_model.h > @@ -158,6 +158,26 @@ struct em_data_callback { > */ > int (*get_cost)(struct device *dev, unsigned long freq, > unsigned long *cost); > + > + /** > + * update_power() - Provide new power at the given performance state of > + * a device > + * @dev : Device for which we do this operation (can be a CPU) > + * @freq : Frequency at the performance state in kHz > + * @power : New power value at the performance state > + * (modified) > + * @priv : Pointer to private data useful for tracking context > + * during run-time modifications of EM. > + * > + * The update_power() is used by run-time modifiable EM. It aims to > + * provide updated power value for a given frequency, which is stored > + * in the performance state. The power value provided by this callback > + * should fit in the [0, EM_MAX_POWER] range. > + * > + * Return 0 on success, or appropriate error value in case of failure. > + */ > + int (*update_power)(struct device *dev, unsigned long freq, > + unsigned long *power, void *priv); > }; > #define EM_SET_ACTIVE_POWER_CB(em_cb, cb) ((em_cb).active_power = cb) > #define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) \ > @@ -165,6 +185,7 @@ struct em_data_callback { > .get_cost = _cost_cb } > #define EM_DATA_CB(_active_power_cb) \ > EM_ADV_DATA_CB(_active_power_cb, NULL) > +#define EM_UPDATE_CB(_update_power_cb) { .update_power = &_update_power_cb } > > struct em_perf_domain *em_cpu_get(int cpu); > struct em_perf_domain *em_pd_get(struct device *dev);