From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Lin Ming <ming.m.lin@intel.com>, Zhang Rui <rui.zhang@intel.com>,
Jeff Garzik <jgarzik@pobox.com>, Tejun Heo <tj@kernel.org>,
Len Brown <lenb@kernel.org>,
linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org,
linux-scsi@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [RFC PATCH 4/6] PM / Runtime: Introduce flag can_power_off
Date: Mon, 13 Feb 2012 21:50:41 +0100 [thread overview]
Message-ID: <201202132150.42115.rjw@sisk.pl> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1202131534040.11382-100000@iolanthe.rowland.org>
On Monday, February 13, 2012, Alan Stern wrote:
> On Mon, 13 Feb 2012, Rafael J. Wysocki wrote:
>
> > > I'm not sure if this is really the right approach. What you're trying
> > > to do is implement two different low-power states, basically D3hot and
> > > D3cold. Currently the runtime PM core doesn't support such things; all
> > > it knows about is low power and full power.
> >
> > I'd rather say all it knows about is "suspended" and "active", which mean
> > "the device is not processing I/O" and "the device may be processing I/O",
> > respectively. A "suspended" device may or may not be in a low-power state,
> > but the runtime PM core doesn't care about that.
>
> Yes, okay. We can say that this patch tries to implement two different
> "suspended" states, basically "low power" and "power off" (or D3hot and
> D3cold).
>
> > > Before doing an ad-hoc implementation, it would be best to step back
> > > and think about other subsystems. Other sorts of devices may well have
> > > multiple low-power states. What's the best way for this to be
> > > supported by the PM core?
> >
> > Well, I honestly don't think there's any way they all can be covered at the
> > same time and that's why we chose to support only "suspended" and "active"
> > as defined above. The handling of multiple low-power states must be
> > implemented outside of the runtime PM core (like in the PCI core, for example).
>
> That's the point. If this is to be implemented outside of the runtime
> PM core, should the patch be allowed to add new fields to struct
> dev_pm_info (which has to be shared among all subsystems)?
>
> Or to put it another way, if we do add new fields to struct dev_pm_info
> (like can_power_off) in order to help support multiple "suspended"
> states, shouldn't these new fields be such that they can be used by
> many different subsystems rather than being special for the
> full-power/no-power situation?
>
> Likewise, should new routines like pm_runtime_allow_power_off() be
> added to the runtime PM core if they are going to be used just by PCI?
No, they shouldn't.
Thanks,
Rafael
next prev parent reply other threads:[~2012-02-13 20:46 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-13 9:11 [RFC] ACPI D3Cold state and SATA ZPODD support Lin Ming
2012-02-13 9:11 ` [RFC PATCH 1/6] ACPI: Introduce ACPI D3_COLD state support Lin Ming
2012-02-13 20:25 ` Rafael J. Wysocki
2012-02-14 7:07 ` Zhang Rui
2012-02-14 22:29 ` Rafael J. Wysocki
2012-02-16 7:08 ` Zhang Rui
2012-02-17 22:23 ` Rafael J. Wysocki
2012-02-20 5:39 ` Zhang Rui
2012-02-13 9:11 ` [RFC PATCH 2/6] ACPI: Reference devices in ACPI Power Resource Lin Ming
2012-02-13 20:48 ` Rafael J. Wysocki
2012-02-14 7:59 ` Zhang Rui
2012-02-14 22:36 ` Rafael J. Wysocki
2012-02-16 7:18 ` Zhang Rui
2012-02-16 15:13 ` Alan Stern
2012-02-17 1:12 ` Lin Ming
2012-02-17 22:37 ` Rafael J. Wysocki
2012-02-17 7:05 ` Zhang, Rui
2012-02-17 15:07 ` Alan Stern
2012-02-21 14:07 ` Lin Ming
2012-02-21 16:06 ` Alan Stern
2012-02-23 13:41 ` Lin Ming
2012-02-23 18:10 ` Alan Stern
2012-02-17 22:34 ` Rafael J. Wysocki
2012-02-20 5:43 ` Zhang Rui
2012-02-13 9:11 ` [RFC PATCH 3/6] ACPI: Runtime resume all devices covered by a power resource Lin Ming
2012-02-13 9:11 ` [RFC PATCH 4/6] PM / Runtime: Introduce flag can_power_off Lin Ming
2012-02-13 15:01 ` Alan Stern
2012-02-13 19:38 ` Rafael J. Wysocki
2012-02-13 20:41 ` Alan Stern
2012-02-13 20:50 ` Rafael J. Wysocki [this message]
2012-02-14 7:11 ` Zhang Rui
2012-02-14 22:38 ` Rafael J. Wysocki
2012-02-14 6:17 ` Zhang Rui
2012-02-14 22:39 ` Rafael J. Wysocki
2012-02-16 7:41 ` Zhang Rui
2012-02-17 23:54 ` Rafael J. Wysocki
2012-02-18 12:54 ` huang ying
2012-02-18 20:35 ` Rafael J. Wysocki
2012-02-20 3:23 ` Zhang Rui
2012-02-20 23:13 ` Rafael J. Wysocki
2012-02-21 1:13 ` Zhang Rui
2012-02-21 21:43 ` Rafael J. Wysocki
2012-02-22 0:57 ` Zhang Rui
2012-02-14 6:07 ` Zhang Rui
2012-02-13 9:11 ` [RFC PATCH 5/6] PCI: Move acpi_dev_run_wake to acpi core Lin Ming
2012-02-13 20:49 ` Rafael J. Wysocki
2012-02-13 9:11 ` [RFC PATCH 6/6] libata: add ZPODD support Lin Ming
2012-02-15 6:06 ` Aaron Lu
2012-02-15 6:46 ` Lin Ming
2012-02-15 7:18 ` Aaron Lu
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