From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lina Iyer Subject: Re: [PATCH 2/9] PM / Domains: Remove dev->driver check for runtime PM Date: Mon, 24 Aug 2015 13:50:32 -0600 Message-ID: <20150824195032.GA1384@linaro.org> References: <1438731339-58317-1-git-send-email-lina.iyer@linaro.org> <1438731339-58317-3-git-send-email-lina.iyer@linaro.org> <7hfv3onv5c.fsf@deeprootsystems.com> <7hwpwylepx.fsf@deeprootsystems.com> <7hio88gxpn.fsf@deeprootsystems.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Received: from mail-pa0-f48.google.com ([209.85.220.48]:33438 "EHLO mail-pa0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754026AbbHXTuf (ORCPT ); Mon, 24 Aug 2015 15:50:35 -0400 Received: by pacti10 with SMTP id ti10so30980387pac.0 for ; Mon, 24 Aug 2015 12:50:34 -0700 (PDT) Content-Disposition: inline In-Reply-To: <7hio88gxpn.fsf@deeprootsystems.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Kevin Hilman Cc: Geert Uytterhoeven , "Rafael J. Wysocki" , Ulf Hansson , Krzysztof =?utf-8?Q?Koz=C5=82owski?= , Linux PM list , "linux-arm-kernel@lists.infradead.org" , "msivasub@codeaurora.org" , Andy Gross , Stephen Boyd On Fri, Aug 21 2015 at 15:04 -0600, Kevin Hilman wrote: >Geert Uytterhoeven writes: > >> Hi Kevin, >> >> On Fri, Aug 14, 2015 at 7:19 PM, Kevin Hilman wrote: >>> On Fri, Aug 14, 2015 at 12:24 AM, Geert Uytterhoeven >>> wrote: >>>> On Fri, Aug 14, 2015 at 5:40 AM, Kevin Hilman wrote: >>>>> Geert Uytterhoeven writes: >>>>>> On Wed, Aug 12, 2015 at 9:50 PM, Kevin Hilman wrote: >>>>>>> This check might have made sense before PM domains, but with PM domains, >>>>>>> it's entirely possible to have a simple device without a driver and the >>>>>>> PM domain handles all the necesary PM, so I think this check >>>>>>> could/should be removed. >>>>>>> >>>>>>> Thoughts? >>>>>> >>>>>> Simple devices without a driver aren't handled automatically. >>>>>> At minimum, the driver should call pm_runtime_enable(), cfr. >>>>>> drivers/bus/simple-pm-bus.c. >>>>> >>>>> That's correct, and in the proof-of-concept stuff I hacked up and in >>>>> Lina's series, the CPU "devices" do indeed to this. Without that, they >>>>> wouldn't end up ever taking this codepath through genpd's >>>>> runtime_suspend and power_off hooks. >>>>> >>>>> Also, I'm not sure if your comment was meant to be an objection to the >>>>> patch? or if you're OK with it. >>>> >>>> My comment was purely meant as a response to "it's entirely possible to have a >>>> simple device without a driver and the PM domain handles all the necesary PM". >>> >>> Right, so if the PM domain does the pm_runtime_enable() for these >>> "simple" devices without drivers, they can still exist without a >>> driver, and the PM domain doing all the magic. >> >> Is it possible to let the PM Domain do the pm_runtime_enable() itself in >> the absence of a driver? > >Well, I suppose it's possible, not sure it's recommended. :) > >> If yes, I wouldn't have needed simple-pm-bus.c. >> What if a driver is bound later? > >Yeah, you're approach is better. > I am not sure I understand the approach? Initialize the CPU devices as "simple-pm-bus" compatible? Thanks, Lina