From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751944AbdECLWH (ORCPT ); Wed, 3 May 2017 07:22:07 -0400 Received: from foss.arm.com ([217.140.101.70]:54674 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751766AbdECLV7 (ORCPT ); Wed, 3 May 2017 07:21:59 -0400 Subject: Re: [PATCH V4 1/9] PM / OPP: Allow OPP table to be used for power-domains To: Mark Brown , robh+dt@kernel.org References: <0a7146f9-72f1-317c-3aab-770a72462968@arm.com> <20170413053736.GM5910@vireshk-i7> <3adbef6a-7b43-528f-e88f-c2121d30a5d3@arm.com> <20170417052758.GF28191@vireshk-i7> <95aa4b97-4e1a-13bb-f4d8-982b778012ba@arm.com> <9cd9287c-392b-d3ca-db7d-75c49287448e@codeaurora.org> <20170426135532.ryrh276znet5yvks@sirena.org.uk> <20170430124917.4m3d237pik7q47f3@sirena.org.uk> Cc: Sudeep Holla , Rajendra Nayak , Viresh Kumar , Rafael Wysocki , ulf.hansson@linaro.org, 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@linaro.org, devicetree@vger.kernel.org From: Sudeep Holla Organization: ARM Message-ID: <8aacc296-2549-f0b8-ac25-2f4000c084c1@arm.com> Date: Wed, 3 May 2017 12:21:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170430124917.4m3d237pik7q47f3@sirena.org.uk> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30/04/17 13:49, Mark Brown wrote: > On Thu, Apr 27, 2017 at 10:42:49AM +0100, Sudeep Holla wrote: >> On 26/04/17 14:55, Mark Brown wrote: > >>> As I'm getting fed up of saying: if the values you are setting are not >>> voltages and do not behave like voltages then the hardware should not be >>> represented as a voltage regulator since if they are represented as >>> voltage regulators things will expect to be able to control them as >>> voltage regulators. This hardware is quite clearly providing OPPs >>> directly, I would expect this to be handled in the OPP code somehow. > >> I agree with you that we need to be absolutely sure on what it actually >> represents. > >> But as more and more platform are pushing such power controls to >> dedicated M3 or similar processors, we need abstraction. Though we are >> controlling hardware, we do so indirectly. Since there were discussions >> around device tree representing hardware vs platform, I tend to think, >> we are moving towards platform(something similar to ACPI). > > I don't think there's a meaningful hardware/platform distinction here - > in terms of what DT is describing the platform bit is just what the > hardware (the microcontrollers) happen to do, > Yes agreed. It's similar to PSCI or any other platform firmware IMO. The question is how do we deal with such controls that needs to be done via the firmware ? We generally plug-in to the existing framework in Linux using the existing bindings. Most of the time, much simpler bindings than the one that present complete hardware description. > DT doesn't much care about that though. No sure about that, may be doesn't care about the internals, but we need to care about interface, no ? -- Regards, Sudeep