From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Li, Aubrey" Subject: Re: [PATCH 5/6] intel_idle: Add ->enter_freeze callbacks Date: Thu, 05 Mar 2015 08:09:10 +0800 Message-ID: <54F79EA6.2030605@linux.intel.com> References: <8292243.ibkmfVtXac@vostro.rjw.lan> <25445086.IBiaGBbm1j@vostro.rjw.lan> <54F79A42.9070801@linux.intel.com> <2502414.MyBzvuWGMR@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <2502414.MyBzvuWGMR@vostro.rjw.lan> Sender: linux-kernel-owner@vger.kernel.org To: "Rafael J. Wysocki" Cc: Peter Zijlstra , Thomas Gleixner , Alan Cox , LKML , Linux PM list , ACPI Devel Maling List , Kristen Carlson Accardi , John Stultz , Len Brown List-Id: linux-pm@vger.kernel.org On 2015/3/5 8:18, Rafael J. Wysocki wrote: > On Thursday, March 05, 2015 07:50:26 AM Li, Aubrey wrote: >> On 2015/2/13 0:24, Rafael J. Wysocki wrote: >>> On Thursday, February 12, 2015 02:26:43 PM Peter Zijlstra wrote: >>>> >>>> Why bother with enter_freeze() for any but the deepest state (C6 in this >>>> case)? >>> >>> User space may disable the deepest one (and any of them in general) via sysfs >>> and there's no good reason to ignore its choice in this particular case while >>> we're honoring it otherwise. >>> >>> So the logic is basically "find the deepest one which isn't disabled" and >>> setting the pointers costs us nothing really. >>> >> >> If the user has chance to disable C6 via /sys, that means c6 works? >> Shouldn't we ignore user space setting during freeze? Otherwise, we will >> lost S0ix? > > We can't ignore it, because we don't know the reason why the state was > disabled. > > It may just not work reliably enough on the given platform. > okay, make sense to me. Thanks, -Aubrey