Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932575Ab2BNWZb (ORCPT ); Tue, 14 Feb 2012 17:25:31 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:52454 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761299Ab2BNWZZ convert rfc822-to-8bit (ORCPT ); Tue, 14 Feb 2012 17:25:25 -0500 From: "Rafael J. Wysocki" To: Zhang Rui Subject: Re: [RFC PATCH 1/6] ACPI: Introduce ACPI D3_COLD state support Date: Tue, 14 Feb 2012 23:29:16 +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> <201202132125.15537.rjw@sisk.pl> <1329203228.19384.35.camel@rui.sh.intel.com> In-Reply-To: <1329203228.19384.35.camel@rui.sh.intel.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Message-Id: <201202142329.16516.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4433 Lines: 115 On Tuesday, February 14, 2012, Zhang Rui wrote: > Hi, Rafael, > > On δΈ€, 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. > 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). 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/