From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756360Ab2DHXnL (ORCPT ); Sun, 8 Apr 2012 19:43:11 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:59181 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752387Ab2DHXnK convert rfc822-to-8bit (ORCPT ); Sun, 8 Apr 2012 19:43:10 -0400 From: "Rafael J. Wysocki" To: Lin Ming Subject: Re: [PATCH] ACPI: evaluate _PS3 when entering D3 Cold Date: Mon, 9 Apr 2012 01:47:36 +0200 User-Agent: KMail/1.13.6 (Linux/3.3.0+; KDE/4.6.0; x86_64; ; ) 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 References: <1333217910-29579-1-git-send-email-aaron.lu@amd.com> <201204010923.18330.rjw@sisk.pl> <1333593080.11327.22.camel@minggr> In-Reply-To: <1333593080.11327.22.camel@minggr> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Message-Id: <201204090147.36529.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, April 05, 2012, Lin Ming wrote: > 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. > > I don't understand item (2): > > If the power resource is listed as "off", which means it's already > turned off. Then why should it be turned off again? Sorry, there are two lists. One of them is returned by _PR0 (these are needed to put the device into D0) and the second is returned by _PR3 (if that exists) and these need to be "on" for the device to stay in D3_hot (if they are "off", the device will go into D3_cold instead). Actually, section 7.2.11 of ACPI 5.0 is quite clear in that respect. > Let's see an example > > Assume a device "dev0" depends on 5 power resources: > > pr1, pr2, pr3, pr4, pr5 > > _PR3 lists 3 power resources: pr3, pr4, pr5 > > Device(dev0) > { > Name(_PR3, Package (0x03) > { > pr3, > pr4, > pr5 > }) > } > > If dev0 is put into ACPI D3_hot and pr1 and pr2 are not referenced by > other devices, then it requires: > > - pr1 and pr2 are off > - pr3, pr4 and pr5 are on > > right? That's correct. Thanks, Rafael