From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751786Ab2DAHpS (ORCPT ); Sun, 1 Apr 2012 03:45:18 -0400 Received: from mga02.intel.com ([134.134.136.20]:59517 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750770Ab2DAHpP (ORCPT ); Sun, 1 Apr 2012 03:45:15 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,352,1309762800"; d="scan'208";a="124144669" Message-ID: <1333266346.2387.110.camel@rui.sh.intel.com> Subject: Re: [PATCH] ACPI: evaluate _PS3 when entering D3 Cold From: Zhang Rui To: "Rafael J. Wysocki" Cc: Lin Ming , Aaron Lu , Len Brown , linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Andiry Xu , Alex He Date: Sun, 01 Apr 2012 15:45:46 +0800 In-Reply-To: <201204010923.18330.rjw@sisk.pl> References: <1333217910-29579-1-git-send-email-aaron.lu@amd.com> <20120401055603.GA11505@localhost.amd.com> <1333261737.2939.84.camel@minggr> <201204010923.18330.rjw@sisk.pl> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.2 (3.2.2-1.fc16) Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 日, 2012-04-01 at 09:23 +0200, Rafael J. Wysocki wrote: > Hi, > > Sorry for the delayed response, I've been travelling recently. > > On Sunday, April 01, 2012, Lin Ming wrote: > > On Sun, 2012-04-01 at 13:56 +0800, Aaron Lu wrote: > > > Hi, > > > > > > On Sun, Apr 01, 2012 at 01:27:33PM +0800, Lin Ming wrote: > > > > > - if (device->power.states[state].flags.explicit_set) { > > > > > + /* If state is D3 Cold, try to evaluate _PS3 first */ > > > > > + if (state == ACPI_STATE_D3_COLD) { > > > > > + explicit_set = (ps - 1)->flags.explicit_set; > > > > > + object_name[3] -= 1; > > > > > + } > > > > > > > > I'm not sure whether this works or not. > > > > > > > > From ACPI spec, > > > > > > > > _PS3 "is used to put the specific device into its D3hot or D3 state" > > > > > > > > D3 neither means D3hot nor D3cold. It's an old term before D3hot and > > > > D3cold were introduced. > > > I guess D3 has to mean something, right? :-) > > Well, not necessarily. > > The problem is what state the _PS3 method puts the device into: D3_hot or > D3_cold. > > Unfortunately, as far as I can say, ACPI 4.0 didn't specify any "official" > mapping between the "old" D3 and the "new" D3_{hod|cold} states, so we need to > figure out something. In my opinion, the only reasonable approach is to > assume that the state _PS3 puts the device into is always D3_cold, becuase > _PS3 may remove power completely from the device. It may not do that, but > we _must_ assume it does that in general. > There is a problem that I can think of. Say currently, ACPI always returns D3 when _PS3 exists. And this "ACPI_STATE_D3" is translated to PCI_D3hot. But with this approach, we're going to put these devices to PCI_D3cold instead, right? I'm not against this approach, but this may affect a lot of PCI devices, which we need to take care of, no? thanks, rui