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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT 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 196AFC468BD for ; Fri, 7 Jun 2019 15:31:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E78EB2089E for ; Fri, 7 Jun 2019 15:31:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729880AbfFGPbU (ORCPT ); Fri, 7 Jun 2019 11:31:20 -0400 Received: from foss.arm.com ([217.140.110.172]:42804 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729293AbfFGPbT (ORCPT ); Fri, 7 Jun 2019 11:31:19 -0400 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 069B2499; Fri, 7 Jun 2019 08:31:19 -0700 (PDT) Received: from e107155-lin (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 55FE43F718; Fri, 7 Jun 2019 08:31:16 -0700 (PDT) Date: Fri, 7 Jun 2019 16:31:14 +0100 From: Sudeep Holla To: Ulf Hansson Cc: Lorenzo Pieralisi , Mark Rutland , linux-arm-kernel@lists.infradead.org, "Rafael J . Wysocki" , Daniel Lezcano , "Raju P . L . S . S . S . N" , Amit Kucheria , Bjorn Andersson , Stephen Boyd , Niklas Cassel , Tony Lindgren , Kevin Hilman , Lina Iyer , Viresh Kumar , Vincent Guittot , Geert Uytterhoeven , Souvik Chakravarty , Sudeep Holla , linux-pm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 15/18] drivers: firmware: psci: Support CPU hotplug for the hierarchical model Message-ID: <20190607153114.GI15577@e107155-lin> References: <20190513192300.653-1-ulf.hansson@linaro.org> <20190513192300.653-16-ulf.hansson@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190513192300.653-16-ulf.hansson@linaro.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Mon, May 13, 2019 at 09:22:57PM +0200, Ulf Hansson wrote: > When the hierarchical CPU topology is used and when a CPU has been put > offline (hotplug), that same CPU prevents its PM domain and thus also > potential master PM domains, from being powered off. This is because genpd > observes the CPU's attached device as being active from a runtime PM point > of view. > > To deal with this, let's decrease the runtime PM usage count by calling > pm_runtime_put_sync_suspend() of the attached struct device when putting > the CPU offline. Consequentially, we must then increase the runtime PM > usage count, while putting the CPU online again. > Why is this firmware/driver specific ? Why can't this be dealt in core pm-domain ? I am concerned that if any other architectures or firmware method decides to use this feature, this need to be duplicated there. The way I see this is pure reference counting and is hardware/firmware/ driver agnostic and can be made generic. -- Regards, Sudeep