From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [PATCH 4/4] cpuidle - support multiple drivers Date: Thu, 04 Oct 2012 16:26:49 +0200 Message-ID: <506D9CA9.8000308@linaro.org> References: <1348526634-19029-1-git-send-email-daniel.lezcano@linaro.org> <1348526634-19029-5-git-send-email-daniel.lezcano@linaro.org> <20121004141425.GK13834@tbergstrom-lnx.Nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:47467 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964963Ab2JDO0y (ORCPT ); Thu, 4 Oct 2012 10:26:54 -0400 Received: by mail-bk0-f46.google.com with SMTP id jk13so348746bkc.19 for ; Thu, 04 Oct 2012 07:26:53 -0700 (PDT) In-Reply-To: <20121004141425.GK13834@tbergstrom-lnx.Nvidia.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Peter De Schrijver Cc: "rjw@sisk.pl" , "lenb@kernel.org" , "linux-pm@vger.kernel.org" , "lorenzo.pieralisi@arm.com" , "linux-acpi@vger.kernel.org" , "patches@linaro.org" , "linaro-dev@lists.linaro.org" On 10/04/2012 04:14 PM, Peter De Schrijver wrote: > On Tue, Sep 25, 2012 at 12:43:54AM +0200, Daniel Lezcano wrote: >> With the tegra3 and the big.LITTLE [1] new architectures, several cp= us >> with different characteristics (latencies and states) can co-exists = on the >> system. >> >> The cpuidle framework has the limitation of handling only identical = cpus. >> >> This patch removes this limitation by introducing the multiple drive= r support >> for cpuidle. >> >> This option is configurable at compile time and should be enabled fo= r the >> architectures mentioned above. So there is no impact for the other p= latforms >> if the option is disabled. The option defaults to 'n'. Note the mult= iple drivers >> support is also compatible with the existing drivers, even if just o= ne driver is >> needed, all the cpu will be tied to this driver using an extra small= chunk of >> processor memory. >> >> The multiple driver support use a per-cpu driver pointer instead of = a global >> variable and the accessor to this variable are done from a cpu conte= xt. >> >> In order to keep the compatibility with the existing drivers, the fu= nction >> 'cpuidle_register_driver' and 'cpuidle_unregister_driver' will regis= ter >> the specified driver for all the cpus. >> >> The sysfs output for the 'current_driver' is changed when this optio= n is >> set by giving the drivers per cpu. >> >> eg. >> cpu0: acpi_idle >> cpu1: acpi_idle >> >=20 > Is this allowed? I thought sysfs files can output only 1 line of data= ? Ah yeah :) Does it make sense to put the following files: /sys/devices/system/cpu/cpu0/cpuidle/driver =3D> acpi_idle /sys/devices/system/cpu/cpu1/cpuidle/driver =3D> acpi_idle and the content of the file: /sys/devices/system/cpu/cpuidle/current_driver will show the driver associated with current cpu ? --=20 Linaro.org =E2=94=82 Open source software for= ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html