Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755076AbaKTNMo (ORCPT ); Thu, 20 Nov 2014 08:12:44 -0500 Received: from mail-qg0-f54.google.com ([209.85.192.54]:62770 "EHLO mail-qg0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750953AbaKTNMm (ORCPT ); Thu, 20 Nov 2014 08:12:42 -0500 MIME-Version: 1.0 In-Reply-To: <546DD87B.3080806@ti.com> References: <1415631557-22897-1-git-send-email-grygorii.strashko@ti.com> <1709760.E0jX3Myv0h@wuerfel> <546C7FDD.7030906@ti.com> <2900095.WIocOu7ue2@wuerfel> <546DD87B.3080806@ti.com> Date: Thu, 20 Nov 2014 14:12:41 +0100 Message-ID: Subject: Re: [PATCH v4 1/2] ARM: keystone: pm: switch to use generic pm domains From: Ulf Hansson To: Grygorii Strashko Cc: Arnd Bergmann , Kevin Hilman , ssantosh@kernel.org, "Rafael J. Wysocki" , "linux-pm@vger.kernel.org" , Rob Herring , Grant Likely , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , Geert Uytterhoeven , Dmitry Torokhov Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20 November 2014 13:03, Grygorii Strashko wrote: > On 11/20/2014 01:34 PM, Ulf Hansson wrote: >> On 19 November 2014 14:47, Arnd Bergmann wrote: >>> On Wednesday 19 November 2014 13:32:45 Grygorii Strashko wrote: >>>> On 11/18/2014 09:32 PM, Arnd Bergmann wrote: >>>>> On Tuesday 18 November 2014 20:54:36 Grygorii Strashko wrote: >>>>> >>>>> Have one pmdomain driver in the generic code that knows about clocks, >>>>> possibly also regulators and pins and just turns them on when needed. >>>>> You can have a "simple-pmdomain" or "generic-pmdomain" compatible >>>>> string. >>>>> >>>>> I'm a bit surprised that your pmdomain code looks up the clocks from the >>>>> respective device, rather than know about the clocks itself. There is >>>>> probably a good reason for this, but I don't see it yet. >>>> >>>> The keystone 2 uses simple PM schema based on clocks only: >>>> - clocks enabled -> dev is active >>>> - clocks disabled -> dev is suspended >>>> >>>> To achieve explained above the Generic clock manipulation PM callbacks framework (pm_clk) is used. >>>> - list of managed clocks is filled for each device (for non-DT case the con_id list >>>> is specified by platform code like: >>>> .con_ids = { "fck", "master", "slave", NULL }, >>>> - or - >>>> .con_ids = { }, <-- in this case only first clock will be added to pm_clk >>>> ) >> >> According to earlier comments in this thread, device's clocks are >> split into "functional" and "PM" clocks. >> >> If I understand correctly, a typical platform driver will enable it's >> "functional" clocks during ->probe() and you want the PM domain to >> take care of the "PM" clocks, when the device changes runtime PM >> status. >> >> How will you describe these different set of device clocks in DT? > > True :( You can dig deeper in the history of this series if you wish. > - first Geert Uytterhoeven proposed to use CLK_RUNTIME_PM there > https://lkml.org/lkml/2014/11/6/319 > - second I proposed to introduce smth. like "clkops-clocks", "pm-clocks" there > https://lkml.org/lkml/2014/6/12/436 > or "fck-clocks"/"opt-clocks" later. > > ^failed. > > So, this implementation picks up all clocks for each device, which is ok for > Keystone 2 and, because it's platform specific. > >>> >>> Yes, it would definitely solve the problem that I see with the infrastructure >>> code that the current version adds into the platform directory. >>> >>> The exact binding of course should be reviewed by the pmdomain and >>> DT maintainers, to ensure that it is done the best possible way, because >>> I assume we will end up using it a lot, and it would be a shame to get >>> it slightly wrong. >>> >>> One possible variation I can think of would be to just use "simple-pmdomain" >>> as the compatible string, and use properties in the node itself to decide >>> what the domain should control, e.g. >>> >>> clk_pmdomain: pmdomain { >>> compatible = "simple-pmdomain"; >>> pmdomain-enable-clocks; >>> #power-domain-cells = <0>; >>> }; >>> clk_regulator_pmdomain: pmdomain { >>> compatible = "simple-pmdomain"; >>> pmdomain-enable-clocks; >>> pmdomain-enable-regulators; >>> #power-domain-cells = <0>; >>> }; >>> >>> and then have each device link to one of the nodes as the pmdomain. >>> >> >> That's seems like a good approach to me. > > Yes, but your previous comment is still actual :( Agree! So I really think we need to decide on how to address the split of the device clocks. Before that's done, I don't think it make sense to add a "simple-pmdomain" compatible, since it will likely not be that many SoC that can use it. So, does anyone have a suggestion on how to deal with the split of the device clocks into "functional" clocks and into "PM" clocks? Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/