From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH] ACPI: evaluate _PS3 when entering D3 Cold Date: Sun, 1 Apr 2012 09:23:18 +0200 Message-ID: <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> Mime-Version: 1.0 Content-Type: Text/Plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from ogre.sisk.pl ([217.79.144.158]:47593 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751923Ab2DAHS7 convert rfc822-to-8bit (ORCPT ); Sun, 1 Apr 2012 03:18:59 -0400 In-Reply-To: <1333261737.2939.84.camel@minggr> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Lin Ming 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 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, > >=20 > > 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 =3D=3D ACPI_STATE_D3_COLD) { > > > > + explicit_set =3D (ps - 1)->flags.explicit_set; > > > > + object_name[3] -=3D 1; > > > > + } > > >=20 > > > I'm not sure whether this works or not. > > >=20 > > > From ACPI spec, > > >=20 > > > _PS3 "is used to put the specific device into its D3hot or D3 sta= te" > > >=20 > > > 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 "offici= al" 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 t= o assume that the state _PS3 puts the device into is always D3_cold, becu= ase _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 st= ate > > with _PS3. > >=20 > > And the ACPI does have some words like: > >=20 > > ------ > > Platform/drivers must assume that the device will have power comple= tely > > removed when the device is place into =E2=80=9CD3=E2=80=9D via _PS3 Exactly. What it means is basically "always reinitialize the device fr= om scratch if you have run _PS3 on it". And that's what we should do. > > ------ > >=20 > > This is in section 7.2.11: _PR3. > >=20 > > >=20 > > > Another problem: > > >=20 > > > With your patch, both D3hot and D3cold will evaluate _PS3, right? > > >=20 > > Yes. > >=20 > > > Will it have problem on AMD platform if you try to put ODD into D= 3hot > > > state? _PS3 is evaluated, so it actually enters D3Cold state. > >=20 > > 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 col= d(via > > _PS3). >=20 > But this is the generic code. We can't only consider some special > device. >=20 > 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" sta= te. Our generic code should reflect that. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html