From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [PATCH] PM / suspend: Always use deepest C-state in the "freeze" sleep state Date: Mon, 12 May 2014 16:52:22 +0200 Message-ID: <5370E026.5040105@linaro.org> References: <2548502.zJ1no3NhRc@vostro.rjw.lan> <5370D5E4.5040001@linaro.org> <5370D85C.3090505@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-wg0-f50.google.com ([74.125.82.50]:64599 "EHLO mail-wg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758432AbaELOwO (ORCPT ); Mon, 12 May 2014 10:52:14 -0400 Received: by mail-wg0-f50.google.com with SMTP id x12so7096942wgg.9 for ; Mon, 12 May 2014 07:52:13 -0700 (PDT) In-Reply-To: <5370D85C.3090505@linux.intel.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Li, Aubrey" , "Rafael J. Wysocki" , Linux PM list Cc: Linux Kernel Mailing List , Zhang Rui , Aubrey Li On 05/12/2014 04:19 PM, Li, Aubrey wrote: > On 2014/5/12 22:08, Daniel Lezcano wrote: >> On 05/05/2014 12:51 AM, Rafael J. Wysocki wrote: >>> From: Rafael J. Wysocki >>> >>> If freeze_enter() is called, we want to bypass the current cpuidle >>> governor and always use the deepest available (that is, not disable= d) >>> C-state, because we want to save as much energy as reasonably possi= ble >>> then and runtime latency constraints don't matter at that point, si= nce >>> the system is in a sleep state anyway. >>> >>> Signed-off-by: Rafael J. Wysocki >>> --- >>> >>> This is on top of https://patchwork.kernel.org/patch/4071541/ . >>> >> >> Wouldn't make sense to revisit play_dead instead ? >> > play_dead() is broken. > > Even if it works, we still should rely on cpuidle driver to place the > CPUs into the deepest c-state, because there is no architectural way = to > enter deepest c-state and what play_dead() does is a bad assumption. Ok, let me rephrase it. Why not revisiting cpuidle_play_dead instead ? --=20 Linaro.org =E2=94=82 Open source software fo= r ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog