From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [PATCH 05/18] cpuidle: make a single register function for all Date: Wed, 10 Apr 2013 21:59:09 +0200 Message-ID: <5165C48D.5060303@linaro.org> References: <1365603743-5618-1-git-send-email-daniel.lezcano@linaro.org> <1365603743-5618-6-git-send-email-daniel.lezcano@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-wi0-f173.google.com ([209.85.212.173]:48945 "EHLO mail-wi0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935117Ab3DJT7O (ORCPT ); Wed, 10 Apr 2013 15:59:14 -0400 Received: by mail-wi0-f173.google.com with SMTP id ez12so5217806wid.6 for ; Wed, 10 Apr 2013 12:59:13 -0700 (PDT) In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Colin Cross Cc: "Rafael J. Wysocki" , Linus Walleij , jason@lakedaemon.net, andrew@lunn.ch, Sascha Hauer , Stephen Warren , Santosh Shilimkar , nicolas.ferre@atmel.com, plagnioj@jcrosoft.com, linux@maxim.org.za, Rob Herring , nsekhar@ti.com, horms@verge.net.au, Magnus Damm , Deepthi Dharwar , Paul Mundt , Jiri Kosina , Kukjin Kim , Kevin Hilman , Tony Lindgren , Linux PM list , "patches@linaro.org" , "linux-arm-kernel@lists.infradead.org" , "linaro-kernel@lists.linaro.org" J On 04/10/2013 08:22 PM, Colin Cross wrote: > On Wed, Apr 10, 2013 at 7:22 AM, 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); >> } >> >> This code is duplicated in each cpuidle driver. >> >> On UP systems, it is done this way: >> >> cpuidle_register_driver(drv); >> device =3D &per_cpu(cpuidle_dev, cpu); >> cpuidle_register_device(device); >> >> On UP, the macro 'for_each_cpu' does one iteration: >> >> #define for_each_cpu(cpu, mask) \ >> for ((cpu) =3D 0; (cpu) < 1; (cpu)++, (void)mask) >> >> Hence, the initialization loop is the same for UP than SMP. >> >> Beside, we saw different bugs / mis-initialization / return code unc= hecked in >> the different drivers, the code is duplicated including bugs. After = fixing all >> these ones, it appears the initialization pattern is the same for ev= eryone. >> >> Let's add a wrapper function doing this initialization with a cpumas= k parameter >> for the coupled idle states and use it for all the drivers. >=20 > Isn't this going to cause problems for big.LITTLE, which has two > independent sets of coupled cpus, and may even have different drivers > for the two types of cpu? AFAICT no, because the "low levels" API are still there, I mean cpuidle_register_driver and cpuidle_register_device. That will be up to the b.L driver to use the API which fits its need. --=20 Linaro.org =E2=94=82 Open source software for= ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog