From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [PATCH 2/9] PM / Domains: Remove dev->driver check for runtime PM Date: Thu, 13 Aug 2015 20:40:42 -0700 Message-ID: <7hwpwylepx.fsf@deeprootsystems.com> 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> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from mail-pa0-f49.google.com ([209.85.220.49]:36118 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932081AbbHNDkq (ORCPT ); Thu, 13 Aug 2015 23:40:46 -0400 Received: by pacrr5 with SMTP id rr5so51026571pac.3 for ; Thu, 13 Aug 2015 20:40:45 -0700 (PDT) In-Reply-To: (Geert Uytterhoeven's message of "Thu, 13 Aug 2015 10:57:38 +0200") Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Geert Uytterhoeven Cc: Lina Iyer , "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 Geert Uytterhoeven writes: > Hi Kevin, > > On Wed, Aug 12, 2015 at 9:50 PM, Kevin Hilman wrote: >> Lina Iyer writes: >> >>> Remove check for driver of a device, for runtime PM. Device may be >>> suspended without an explicit driver. This check seems to be vestigial >>> and incorrect in the current context. >> >> This one should probably have been RFC. >> >> For a little more context here, this was uncovered when experimenting >> with using runtime PM for CPU devices which don't have a dev->driver. >> >> 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. Thanks for the feedback, Kevin