From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [V3 patch 06/19] cpuidle: make a single register function for all Date: Tue, 23 Apr 2013 15:43:45 +0200 Message-ID: <51769011.7030608@linaro.org> References: <1365770165-27096-1-git-send-email-daniel.lezcano@linaro.org> <1365770165-27096-7-git-send-email-daniel.lezcano@linaro.org> <516FB35D.7000303@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-ee0-f45.google.com ([74.125.83.45]:43286 "EHLO mail-ee0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755929Ab3DWNoD (ORCPT ); Tue, 23 Apr 2013 09:44:03 -0400 Received: by mail-ee0-f45.google.com with SMTP id l10so265953eei.18 for ; Tue, 23 Apr 2013 06:44:01 -0700 (PDT) In-Reply-To: <516FB35D.7000303@ti.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Santosh Shilimkar Cc: rjw@sisk.pl, linus.walleij@linaro.org, jason@lakedaemon.net, andrew@lunn.ch, kernel@pengutronix.de, swarren@wwwdotorg.org, nicolas.ferre@atmel.com, plagnioj@jcrosoft.com, linux@maxim.org.za, rob.herring@calxeda.com, nsekhar@ti.com, horms@verge.net.au, magnus.damm@gmail.com, deepthi@linux.vnet.ibm.com, lethal@linux-sh.org, jkosina@suse.cz, kgene.kim@samsung.com, khilman@deeprootsystems.com, tony@atomide.com, linux-pm@vger.kernel.org, patches@linaro.org, linux-arm-kernel@lists.infradead.org, linaro-kernel@lists.linaro.org, josephl@nvidia.com On 04/18/2013 10:48 AM, Santosh Shilimkar wrote: > On Friday 12 April 2013 06:05 PM, Daniel Lezcano wrote: >> The usual scheme to initialize a cpuidle driver on a SMP is: >> >> cpuidle_register_driver(drv); >> for_each_possible_cpu(cpu) { >> device =3D &per_cpu(cpuidle_dev, cpu); >> cpuidle_register_device(device); >> } >> > Not exactly related to $subject patch but the driver should > be registered after all devices has been registered to avoid > devices start using the idle state data as soon as it is > registered. In multi CPU system, this race can easily happen. Could you elaborate what problems the system will be facing if a cpu starts using the idle state data as soon as it is registered ? Is there a bug related to this ? > Current CPUIDLE core layer is also written with the assumption > that driver will be registered first and then the devices which > is not mandatory as per typical drive/device model. Yes, that's true. The framework assumes cpuidle_register_driver is called before cpuidle_register_device. > May be you can fix that part while you are creating this common > wrapper. Personally, as that will modify the cpuidle core layer and the changes are not obvious (because of the design of the code) I prefer to do that in a separate patchset if it is worth to do it - if there is a bug related to it, then there is no discussion, we have to do it :) [ ... ] --=20 Linaro.org =E2=94=82 Open source software for= ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog