From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756672Ab2DECiV (ORCPT ); Wed, 4 Apr 2012 22:38:21 -0400 Received: from mga02.intel.com ([134.134.136.20]:36832 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752238Ab2DECiU (ORCPT ); Wed, 4 Apr 2012 22:38:20 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,351,1309762800"; d="scan'208";a="128847548" Subject: Re: [PATCH] ACPI: evaluate _PS3 when entering D3 Cold From: Lin Ming To: "Rafael J. Wysocki" Cc: Aaron Lu , Len Brown , linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Zhang Rui , Andiry Xu , Alex He 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" Date: Thu, 05 Apr 2012 10:38:17 +0800 Message-ID: <1333593497.11327.25.camel@minggr> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 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. > > > > Here is the problem, there is no _PR3 in AMD's implementation, just _PS3. > > > And since _S0W evaluates 4, I've to put this device into D3 cold state > > > with _PS3. > > > > > > And the ACPI does have some words like: > > > > > > ------ > > > Platform/drivers must assume that the device will have power completely > > > removed when the device is place into “D3” via _PS3 > > Exactly. What it means is basically "always reinitialize the device from > scratch if you have run _PS3 on it". And that's what we should do. > > > > ------ > > > > > > This is in section 7.2.11: _PR3. > > > > > > > > > > > Another problem: > > > > > > > > With your patch, both D3hot and D3cold will evaluate _PS3, right? > > > > > > > Yes. > > > > > > > Will it have problem on AMD platform if you try to put ODD into D3hot > > > > state? _PS3 is evaluated, so it actually enters D3Cold state. > > > > > > There is no D3 hot support for this device(from the firmware's > > > perspective), either it is at D0(via _PS0), or it will be at D3 cold(via > > > _PS3). > > > > But this is the generic code. We can't only consider some special > > device. > > > > Maybe we need some flag to tell which D3 state _PS3 is used for. > > No, please. As I said above, we need to reinitialize devices that _PS3 was > executed on, which is equivalent to saying that those devices were put into > D3_cold. > > The only situation where a device can be put into ACPI D3_hot (which is not > the same as PCI D3_hot, mind you) is when: > > (1) There is _PR3 listing some of the device's power resources as "on". > (2) The power resources listed by the _PR3 as "off" are turned off and the > power resources listed by the _PR3 as "on" are left in the "on" state. (1) and (2) seems conflict. (1) means all power resources listed in _PR3 are "on", but (2) means some power resources listed in _PR3 are "off" and others are "on" Is my understanding correct? Thanks, Lin Ming > > Our generic code should reflect that. > > Thanks, > Rafael