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 17:05:21 +0200 Message-ID: <51657FB1.6030209@linaro.org> References: <1365603743-5618-1-git-send-email-daniel.lezcano@linaro.org> <1365603743-5618-6-git-send-email-daniel.lezcano@linaro.org> <51657E61.9010701@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-ee0-f42.google.com ([74.125.83.42]:49257 "EHLO mail-ee0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935620Ab3DJPFZ (ORCPT ); Wed, 10 Apr 2013 11:05:25 -0400 Received: by mail-ee0-f42.google.com with SMTP id d4so295865eek.29 for ; Wed, 10 Apr 2013 08:05:24 -0700 (PDT) In-Reply-To: <51657E61.9010701@gmail.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Rob Herring Cc: rjw@sisk.pl, andrew@lunn.ch, khilman@deeprootsystems.com, nsekhar@ti.com, josephl@nvidia.com, kgene.kim@samsung.com, patches@linaro.org, magnus.damm@gmail.com, tony@atomide.com, plagnioj@jcrosoft.com, linaro-kernel@lists.linaro.org, jason@lakedaemon.net, swarren@wwwdotorg.org, rob.herring@calxeda.com, horms@verge.net.au, linux@maxim.org.za, linux-arm-kernel@lists.infradead.org, deepthi@linux.vnet.ibm.com, jkosina@suse.cz, linux-pm@vger.kernel.org, lethal@linux-sh.org, kernel@pengutronix.de On 04/10/2013 04:59 PM, Rob Herring wrote: > On 04/10/2013 09:22 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. >> >> That will save a lot of LOC, consolidate the code, and the modificat= ions in the >> future could be done in a single place. Another benefit is the conso= lidation of >> the cpuidle_device variable which is now in the cpuidle framework an= d no longer >> spread accross the different arch specific drivers. >> >> Signed-off-by: Daniel Lezcano >> --- >=20 > Perhaps my ack was too quick... >=20 >> +int cpuidle_register(struct cpuidle_driver *drv, >> + const struct cpumask *const coupled_cpus) >> +{ >> + int ret, cpu; >> + struct cpuidle_device *device; >> + >> + ret =3D cpuidle_register_driver(drv); >> + if (ret) { >> + printk(KERN_ERR "failed to register cpuidle driver\n"); >> + return ret; >> + } >> + >> + for_each_possible_cpu(cpu) { >> + device =3D &per_cpu(cpuidle_dev, cpu); >> + device->cpu =3D cpu; >> +#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED >> + device->coupled_cpus =3D *coupled_cpus; >=20 > This needs a NULL check. CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED is most > likely going to be enabled with multi-platform kernels and this will = crash. Good point, I will fix it. > Also, I think typically struct copies have a note that it is copy. >=20 > Rob >=20 --=20 Linaro.org =E2=94=82 Open source software for= ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog