From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756065AbaD1XLj (ORCPT ); Mon, 28 Apr 2014 19:11:39 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:65167 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755711AbaD1XLg (ORCPT ); Mon, 28 Apr 2014 19:11:36 -0400 From: "Rafael J. Wysocki" To: Daniel Lezcano 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 Date: Tue, 29 Apr 2014 01:28:03 +0200 Message-ID: <2000825.kO1es8ShkW@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.14.0-rc7+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <535E3818.2040905@linaro.org> References: <2471963.urOyfY8mOG@vostro.rjw.lan> <6832089.A5AOPipfbA@vostro.rjw.lan> <535E3818.2040905@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.