From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751986Ab2DUBhJ (ORCPT ); Fri, 20 Apr 2012 21:37:09 -0400 Received: from am1ehsobe001.messaging.microsoft.com ([213.199.154.204]:42810 "EHLO am1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751261Ab2DUBhG (ORCPT ); Fri, 20 Apr 2012 21:37:06 -0400 X-SpamScore: -12 X-BigFish: VPS-12(zzc89bh936eK1432N98dKzz1202hzzz2dh668h839h941hd25h) X-Forefront-Antispam-Report: CIP:163.181.249.109;KIP:(null);UIP:(null);IPV:NLI;H:ausb3twp02.amd.com;RD:none;EFVD:NLI X-WSS-ID: 0M2T353-02-12F-02 X-M-MSG: From: "Lu, Aaron" To: "Rafael J. Wysocki" CC: Lin Ming , Len Brown , linux-acpi , "linux-kernel@vger.kernel.org" , Zhang Rui , "Huang, Ying" Subject: Re: [PATCH v2] ACPI: D3 states cleanup Thread-Topic: [PATCH v2] ACPI: D3 states cleanup Thread-Index: AQHNHpOrWF7Jlsxu+k2twS9uk1hIcJai++GA//+Jk4CAAKizgP//ffaAgACqbID//7NDAAAu7bmX Date: Sat, 21 Apr 2012 01:36:36 +0000 Message-ID: References: <1334884749.4927.6.camel@minggr> <1334900255.4927.36.camel@minggr> <20120420074725.GA30140@localhost.amd.com>,<201204201312.54949.rjw@sisk.pl> In-Reply-To: <201204201312.54949.rjw@sisk.pl> Accept-Language: zh-CN, en-US Content-Language: zh-CN X-MS-Has-Attach: X-MS-TNEF-Correlator: Content-Type: text/plain; charset="gb2312" MIME-Version: 1.0 X-OriginatorOrg: amd.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id q3L1cGOi007981 2012-4-207:08"Rafael J. Wysocki" д > On Friday, April 20, 2012, Aaron Lu wrote: >> Hi, >> >> On Fri, Apr 20, 2012 at 01:37:35PM +0800, Lin Ming wrote: >>>>>>> There are two ACPI D3 states defined now: >>>>>>> ACPI_STATE_D3 and ACPI_STATE_D3_COLD. >>>>>>> >>>>>>> But the uses of these states are not clear/correct in some code. >>>>>>> For example, some code refer ACPI_STATE_D3 as D3hot and others refer >>>>>>> it as D3cold. >>>>>>> >>>>>>> This patch introduces ACPI_STATE_D3_HOT to refer to ACPI D3hot state. >>>>>>> And changes ACPI_STATE_D3 to refer to ACPI D3cold state only. >>>>>>> Also redefines ACPI_STATE_D3_COLD the same as ACPI_STATE_D3. >>>>>>> >>>>>> >>>>>> With this patch now, if a device has _PS3, then we will set its D3hot >>>>>> flag valid. This doesn't feel right to me, since per our discussion the >>>>>> other day, we should assume _PS3 will put the device into D3cold. >>>>>> >>>>>> Or do you mean: if _PS3 is available, then both D3hot and D3cold is >>>>>> valid from the perspective of acpi, it is the individual driver's >>>>>> responsibility to decide which state is actually valid and will be used. >>>>> >>>>> Right. >>>>> >>>>> ACPI_STATE_D3(same as ACPI_STATE_D3_COLD now) is always valid. >>>>> >>>> >>>> I mean, if _PS3 is available, can we say D3hot is valid? >>> >>> Yes. >>> >> >> OK, now I'm confused... >> >> First, let me try to clarify the meaning of acpi power state's valid >> flag. >> >> By valid, I suppose it means the device can be in that state, instead of >> we have a way to program this device to go into that state. >> >> e.g. D0 is valid means the device can be in D0 state, and D3_cold is >> valid means the device can be in D3_cold state. We unconditionally set >> these two states as valid, because we know every device supports these >> two states. But we might not be able to put the device into that state >> in software, since we might not have _PS0 or _PS3 control methods for it. >> >> And if we do have the _PSx or _PRx control methods, we knows we have a >> way to put the device into that state, and hence the device should be >> able to support that power state, so we will set that state as valid too. >> >> Is this correct? >> >> For D3hot, obviously not all device supports this state, so we will need >> to figure it out through the acpi table. >> I remembered Rafael said the following words the other day in a reply to >> my evaluate_ps3_when_entering_d3_cold_patch: >> >> ----------------------------------------------------------------------- >> I'd rather say that with _PR3 we have the opportunity to avoid removing >> power completely from the device. In other words, D3_hot is supported (and >> it is supported _only_ in that case). >> ----------------------------------------------------------------------- >> >> So I think here is a problem, that if a device has only _PS3, why should >> we say D3hot is supported? Is there a reason for this that I missed? > > OK, I agree. We need to special case the situation in which _PR3 is not > present, but _PS3 is. IOW, we should do something like this in the loop in > acpi_bus_get_power_flags(): > > > /* State is valid if we have some power control */ > if (ps->resources.count > || (ps->flags.explicit_set && i < ACPI_STATE_D3)) > ps->flags.valid = 1; > Looks good to me, thanks. -Aaron {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I