Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754959Ab2BQWTe (ORCPT ); Fri, 17 Feb 2012 17:19:34 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:58702 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752933Ab2BQWTc convert rfc822-to-8bit (ORCPT ); Fri, 17 Feb 2012 17:19:32 -0500 From: "Rafael J. Wysocki" To: Zhang Rui Subject: Re: [RFC PATCH 1/6] ACPI: Introduce ACPI D3_COLD state support Date: Fri, 17 Feb 2012 23:23:17 +0100 User-Agent: KMail/1.13.6 (Linux/3.3.0-rc3+; KDE/4.6.0; x86_64; ; ) Cc: Lin Ming , Jeff Garzik , Alan Stern , Tejun Heo , Len Brown , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, linux-pm@vger.kernel.org, ACPI Devel Mailing List References: <1329124271-29464-1-git-send-email-ming.m.lin@intel.com> <201202142329.16516.rjw@sisk.pl> <1329376106.28581.5.camel@rui.sh.intel.com> In-Reply-To: <1329376106.28581.5.camel@rui.sh.intel.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Message-Id: <201202172323.18022.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5289 Lines: 128 On Thursday, February 16, 2012, Zhang Rui wrote: > On 二, 2012-02-14 at 23:29 +0100, Rafael J. Wysocki wrote: > > On Tuesday, February 14, 2012, Zhang Rui wrote: > > > Hi, Rafael, > > > > > > On 一, 2012-02-13 at 21:25 +0100, Rafael J. Wysocki wrote: > > > > On Monday, February 13, 2012, Lin Ming wrote: > > > > > From: Zhang Rui > > > > > > > > > > If a device has _PR3._ON, it means the device supports D3_HOT. > > > > > If a device has _PR3._OFF, it means the device supports D3_COLD. > > > > > Add the ability to validate and enter D3_COLD state in ACPI. > > > > > > > > > > Signed-off-by: Zhang Rui > > > > > > > > This is supposed to be ACPI 5.0 support, right? > > > > > > > No, D3_HOT is introduced in ACPI spec 4.0. > > > According to the spec, _PR3 is used for devices that support both > > > D3(D3_COLD) and D3HOT. > > > > Yes, it does. > > > > > The confusion here is that Linux D3 equals ACPICA D3HOT and Linux > > > D3_COLD equals ACPICA D3. > > > For example, when enter Linux ACPI D3, the reference count of ACPI Power > > > Resources in _PR3 is increased by one. > > > > That's correct. > > > > > > So can anyone please tell me what part of the ACPI 5.0 spec is the > > > > basis of this patch, because I can't see that immediately? > > > > > > > > The only places where D3Cold is _mentioned_ are Section 7.2.12 (_PRE, which > > > > appears to be new in 5.0), Section 7.2.20 (_S0W), Section 7.2.21 (_S1W), > > > > Section 7.2.22 (_S2W), Section 7.2.23 (_S3W) and Section 7.2.24 (_S4W). > > > > None of them mentions those _PR3._ON and _PR3._OFF things above. > > > > > > > > Moreover, my understanding of the spec is that D3Cold means all of the > > > > power resources returned by _PR3 are "off" (whereas some of them will be > > > > "on" in D3hot). > > > > > > > Agreed. > > > > > > > > --- > > > > > drivers/acpi/power.c | 4 ++-- > > > > > drivers/acpi/scan.c | 10 +++++++++- > > > > > 2 files changed, 11 insertions(+), 3 deletions(-) > > > > > > > > > > diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c > > > > > index 9ac2a9f..0d681fb 100644 > > > > > --- a/drivers/acpi/power.c > > > > > +++ b/drivers/acpi/power.c > > > > > @@ -500,14 +500,14 @@ int acpi_power_transition(struct acpi_device *device, int state) > > > > > { > > > > > int result; > > > > > > > > > > - if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3)) > > > > > + if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3_COLD)) > > > > > return -EINVAL; > > > > > > > > > > if (device->power.state == state) > > > > > return 0; > > > > > > > > > > if ((device->power.state < ACPI_STATE_D0) > > > > > - || (device->power.state > ACPI_STATE_D3)) > > > > > + || (device->power.state > ACPI_STATE_D3_COLD)) > > > > > return -ENODEV; > > > > > > > > > > /* TBD: Resources must be ordered. */ > > > > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > > > > > index 8ab80ba..a9d4391 100644 > > > > > --- a/drivers/acpi/scan.c > > > > > +++ b/drivers/acpi/scan.c > > > > > @@ -881,8 +881,16 @@ static int acpi_bus_get_power_flags(struct acpi_device *device) > > > > > > > > > > device->power.flags.power_resources = 1; > > > > > ps->flags.valid = 1; > > > > > - for (j = 0; j < ps->resources.count; j++) > > > > > + for (j = 0; j < ps->resources.count; j++) { > > > > > acpi_bus_add_power_resource(ps->resources.handles[j]); > > > > > + /* Check for D3_COLD support. _PR3._OFF equals D3_COLD ? */ > > > > > + if (i == ACPI_STATE_D3) { > > > > > + if (j == 0) > > > > > + device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1; > > > > > + status = acpi_get_handle(ps->resources.handles[j], "_OFF", &handle); > > > > > + device->power.states[ACPI_STATE_D3_COLD].flags.valid &= ACPI_SUCCESS(status); > > > > > + } > > > > > + } > > > > > > > > Sorry, but this doesn't make sense to me. Power resources always have > > > > the _OFF method, right? > > > > > > > I'm not sure. > > > > That would be explicitly against the spec that says that power resources > > are *required* to have _ON, _OFF and _STA. > > > > > I thought I had seen ACPI Power Resources without _OFF > > > control method somewhere in bugzilla, but I can not find it out now. > > > > That, clearly, is a firmware bug. > > > Okay, agreed. > so how about this? _PR3 equals D3_HOT support. Yes, I can agree with that. :-) > > > Hmm, how about set D3_COLD support if _PR3 exists, but leave a warning > > > message if _OFF doesn't exist, for now? > > > > I don't think we need to set D3_COLD support at all. In fact, it is always > > supported (as I said, if all power resources used by a device are off, the > > device is in D3_COLD pretty much by definition). > > > Yeah, but it seems that Linux uses ACPI_D3 for both ACPICA D3_HOT and D3 > (off). I'm generating a patch to remove ACPI_D3_COLD and introduce > D3_HOT support in Linux kernel. That's a good idea in my opinion. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/