Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757220Ab3G3Dvi (ORCPT ); Mon, 29 Jul 2013 23:51:38 -0400 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:60121 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751883Ab3G3Dvh (ORCPT ); Mon, 29 Jul 2013 23:51:37 -0400 Message-ID: <51F73815.2040406@linux.vnet.ibm.com> Date: Tue, 30 Jul 2013 09:20:45 +0530 From: Deepthi Dharwar User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Daniel Lezcano CC: linux-pm@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] cpuidle/powernv: Enable idle powernv cpu to call into the cpuidle framework. References: <20130723090111.7291.99479.stgit@deepthi.in.ibm.com> <20130723090150.7291.89879.stgit@deepthi.in.ibm.com> <51F35AC7.8060909@linaro.org> <51F67BE5.10701@linux.vnet.ibm.com> <51F67FDE.6070902@linaro.org> In-Reply-To: <51F67FDE.6070902@linaro.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13073014-3568-0000-0000-000004013087 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4025 Lines: 138 On 07/29/2013 08:14 PM, Daniel Lezcano wrote: > On 07/29/2013 04:27 PM, Deepthi Dharwar wrote: >> On 07/27/2013 10:59 AM, Daniel Lezcano wrote: >>> On 07/23/2013 11:01 AM, Deepthi Dharwar wrote: >>>> This patch enables idle powernv cpu to hook on to the cpuidle >>>> framework, if available, else call on to default idle platform >>>> code. >>> >>> Why do you need to do that ? >>> >> >> Hi Daniel, >> >> Well, this is needed in case when one does not compile with CPU_IDLE >> config option. >> >> When CPUIDLE is not configured, idle cpus are needed to be running some >> sort of default idle code or loop ( in the worst case) if cpuidle driver >> is not registered or if one decides not to have that config enabled. > > Hi Deepthi, > > ok may be there is some difference with the other platform but the > arch_cpu_idle function defined in the other archs do: > > void arch_cpu_idle(void) > { > if (cpuidle_idle_call()) > x86_idle(); > else > local_irq_enable(); > } > > or > > void arch_cpu_idle(void) > { > if (cpuidle_idle_call()) > default_idle(); > } > > When the cpuidle driver is not compiled or not loaded, cpuidle_idle_call > fails, falling back to the default idle function. > > The arch_cpu_idle function is called from the generic code in > kernel/cpu/idle.c. > > Is there a particular reason to do it in a different way ? On powerpc, we have another parameter, ppc_md.powersave knob. In arch_cpu_idle, we check for this knob. This is kernel command line parameter too. If this is not set then default idle is executed. ppc_md is generic powerpc structure, which points to idle routine that needs to be executed. In arch_cpu_idle code for powerpc: arch_cpu_idle() { if (ppc_md.powersave()) ppc_md.powersave() } else /* default idle */ } Not all flavors of powerpc arch support cpuidle. So only those that support, powersave is set to cpuidle backend call. And this check is necessary there. Regards, Deepthi > Thanks > -- Daniel > >>> >>>> Signed-off-by: Deepthi Dharwar >>>> --- >>>> arch/powerpc/platforms/powernv/setup.c | 12 +++++++++++- >>>> 1 file changed, 11 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c >>>> index 84438af..97d0951 100644 >>>> --- a/arch/powerpc/platforms/powernv/setup.c >>>> +++ b/arch/powerpc/platforms/powernv/setup.c >>>> @@ -25,6 +25,7 @@ >>>> #include >>>> #include >>>> #include >>>> +#include >>>> >>>> #include >>>> #include >>>> @@ -196,6 +197,15 @@ static int __init pnv_probe(void) >>>> return 1; >>>> } >>>> >>>> +void powernv_idle(void) >>>> +{ >>>> + /* Hook to cpuidle framework if available, else >>>> + * call on default platform idle code >>>> + */ >>>> + if (cpuidle_idle_call()) >>>> + power7_idle(); >>>> +} >>>> + >>>> define_machine(powernv) { >>>> .name = "PowerNV", >>>> .probe = pnv_probe, >>>> @@ -205,7 +215,7 @@ define_machine(powernv) { >>>> .show_cpuinfo = pnv_show_cpuinfo, >>>> .progress = pnv_progress, >>>> .machine_shutdown = pnv_shutdown, >>>> - .power_save = power7_idle, >>>> + .power_save = powernv_idle, >>>> .calibrate_decr = generic_calibrate_decr, >>>> #ifdef CONFIG_KEXEC >>>> .kexec_cpu_down = pnv_kexec_cpu_down, >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >>>> the body of a message to majordomo@vger.kernel.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> Please read the FAQ at http://www.tux.org/lkml/ >>>> >>> >>> >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/