From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758958AbaD3Mkc (ORCPT ); Wed, 30 Apr 2014 08:40:32 -0400 Received: from mail-wi0-f171.google.com ([209.85.212.171]:41097 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757878AbaD3Mkb (ORCPT ); Wed, 30 Apr 2014 08:40:31 -0400 Message-ID: <5360EF3F.1040003@linaro.org> Date: Wed, 30 Apr 2014 14:40:31 +0200 From: Daniel Lezcano User-Agent: Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: "Rafael J. Wysocki" CC: Linux PM list , Linux Kernel Mailing List , Ingo Molnar , Peter Zijlstra Subject: Re: [PATCH 2/2] cpuidle / menu: Return error code if there are no suitable states References: <2471963.urOyfY8mOG@vostro.rjw.lan> <6832089.A5AOPipfbA@vostro.rjw.lan> <535E3818.2040905@linaro.org> <2000825.kO1es8ShkW@vostro.rjw.lan> In-Reply-To: <2000825.kO1es8ShkW@vostro.rjw.lan> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/29/2014 01:28 AM, Rafael J. Wysocki wrote: > On Monday, April 28, 2014 01:14:32 PM Daniel Lezcano wrote: >> On 04/27/2014 02:55 PM, Rafael J. Wysocki wrote: >>> From: Rafael J. Wysocki >>> >>> If there is a PM QoS latency limit and all of the sufficiently shallow >>> C-states are disabled, the cpuidle menu governor returns 0 which on >>> some systems is CPUIDLE_DRIVER_STATE_START and shouldn't be returned >>> if that C-state has been disabled. >>> >>> Fix the issue by modifying the menu governor to return an error code >>> in such situations. >>> >>> Signed-off-by: Rafael J. Wysocki >>> --- >>> drivers/cpuidle/governors/menu.c | 2 +- >>> include/linux/cpuidle.h | 2 ++ >>> 2 files changed, 3 insertions(+), 1 deletion(-) >>> >>> Index: linux-pm/drivers/cpuidle/governors/menu.c >>> =================================================================== >>> --- linux-pm.orig/drivers/cpuidle/governors/menu.c >>> +++ linux-pm/drivers/cpuidle/governors/menu.c >>> @@ -296,7 +296,7 @@ static int menu_select(struct cpuidle_dr >>> data->needs_update = 0; >>> } >>> >>> - data->last_state_idx = 0; >>> + data->last_state_idx = CPUIDLE_DRIVER_STATE_POLL; >>> >>> /* Special case when user has set very strict latency requirement */ >>> if (unlikely(latency_req == 0)) >>> Index: linux-pm/include/linux/cpuidle.h >>> =================================================================== >>> --- linux-pm.orig/include/linux/cpuidle.h >>> +++ linux-pm/include/linux/cpuidle.h >>> @@ -217,8 +217,10 @@ static inline int cpuidle_register_gover >>> >>> #ifdef CONFIG_ARCH_HAS_CPU_RELAX >>> #define CPUIDLE_DRIVER_STATE_START 1 >>> +#define CPUIDLE_DRIVER_STATE_POLL 0 >>> #else >>> #define CPUIDLE_DRIVER_STATE_START 0 >>> +#define CPUIDLE_DRIVER_STATE_POLL (-ENXIO) >>> #endif >>> >>> #endif /* _LINUX_CPUIDLE_H */ >> >> Hi Rafael, >> >> CPUIDLE_DRIVER_STATE_START is only for x86. It introduces some confusion >> in the code. > > I won't disagree with that. > >> As only two drivers are concerned by it, wouldn't make >> sense to add the poll state to those driver directly instead of having >> the code hacked around ? (eg. insert the poll state in the common >> cpuidle code). > > Well, what about initializing data->last_state_idx to > (CPUIDLE_DRIVER_STATE_START - 1) in menu_select() instead of introducing the > new symbol for the time being and getting rid of CPUIDLE_DRIVER_STATE_START > separately? +1 -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog