From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: [PATCH V3 2/7] PM / OPP: Introduce "domain-performance-state" binding to OPP nodes Date: Wed, 1 Mar 2017 14:24:12 +0530 Message-ID: <20170301085412.GF24323@vireshk-i7> References: <20170228003948.ihf4c2ppu2rf3lt2@rob-hp-laptop> <20170228065711.GD19417@vireshk-i7> <20170301061402.GE24323@vireshk-i7> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Geert Uytterhoeven Cc: Rob Herring , Ulf Hansson , Rafael Wysocki , Kevin Hilman , Viresh Kumar , Nishanth Menon , Stephen Boyd , "linaro-kernel@lists.linaro.org" , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Vincent Guittot , Lina Iyer , Rajendra Nayak , "devicetree@vger.kernel.org" List-Id: devicetree@vger.kernel.org On 01-03-17, 09:45, Geert Uytterhoeven wrote: > On Wed, Mar 1, 2017 at 7:14 AM, Viresh Kumar wrote: > > On 28-02-17, 09:52, Rob Herring wrote: > >> On Tue, Feb 28, 2017 at 9:14 AM, Ulf Hansson wrote: > >> > This comes from the early design of the generic PM domain, thus I > >> > assume we have some HW with such complex PM topology. However, I don't > >> > know if it is actually being used. > >> > > >> > Moreover, the corresponding DT bindings for "power-domains" parents, > >> > can easily be extended to cover more than one parent. See more in > >> > Documentation/devicetree/bindings/power/power_domain.txt > >> > >> I could easily see device having 2 power domains. For example a cpu > >> may have separate domains for RAM/caches and logic. > > > > An important thing here is that PM domain doesn't support such devices. i.e. a > > device isn't allowed to have multiple PM domains today. So a way to support such > > devices can be to create a virtual PM domain, that has two parents and device as > > its child. > > As clock domains (and their support code) are fairly orthogonal to power > areas, currently our power area controller driver just forwards the > clock handling > to the clock driver (cfr. rcar-sysc). Perhaps Rajendra can explain better but Qcom have a case where they need to program two power domains as well. -- viresh