From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Linux PM mailing list <linux-pm@lists.linux-foundation.org>,
Kevin Hilman <khilman@ti.com>,
LKML <linux-kernel@vger.kernel.org>, Len Brown <lenb@kernel.org>,
linux-sh@vger.kernel.org, lethal@linux-sh.org,
Magnus Damm <magnus.damm@gmail.com>
Subject: Re: [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones
Date: Thu, 14 Apr 2011 23:12:24 +0000 [thread overview]
Message-ID: <201104150112.24722.rjw@sisk.pl> (raw)
In-Reply-To: <BANLkTiknpAkUQMaq3WZSTHy2cs-vXkv08Q@mail.gmail.com>
On Wednesday, April 13, 2011, Grant Likely wrote:
> On Wed, Apr 13, 2011 at 8:17 AM, Alan Stern <stern@rowland.harvard.edu> wrote:
> > On Wed, 13 Apr 2011, Rafael J. Wysocki wrote:
> >
> >> From: Rafael J. Wysocki <rjw@sisk.pl>
> >>
> >> Change the PM core's behavior related to power domains in such a way
> >> that, if a power domain is defined for a given device, its callbacks
> >> will be executed instead of and not in addition to the device
> >> subsystem's PM callbacks.
> >>
> >> The idea behind the initial implementation of power domains handling
> >> by the PM core was that power domain callbacks would be executed in
> >> addition to subsystem callbacks, so that it would be possible to
> >> extend the subsystem callbacks by using power domains. It turns out,
> >> however, that this wouldn't be really convenient in some important
> >> situations.
> >>
> >> For example, there are systems in which power can only be removed
> >> from entire power domains. On those systems it is not desirable to
> >> execute device drivers' PM callbacks until it is known that power is
> >> going to be removed from the devices in question, which means that
> >> they should be executed by power domain callbacks rather then by
> >> subsystem (e.g. bus type) PM callbacks, because subsystems generally
> >> have no information about what devices belong to which power domain.
> >> Thus, for instance, if the bus type in question is the platform bus
> >> type, its PM callbacks generally should not be called in addition to
> >> power domain callbacks, because they run device drivers' callbacks
> >> unconditionally if defined.
> >
> > What about systems where it makes sense to execute the subsystem
> > callbacks even if power isn't going to be removed from the device?
> > It's quite possible that the subsystem could reduce the device's power
> > consumption even when the device isn't powered down completely.
>
> The understanding Rafael and I came to was that if a power domain is
> attached to a device, then the power domain becomes the responsible
> party. Normally this means it will turn around and immediately call
> the bus_type pm ops, but it has the option to not call them if for a
> particular system it knows better, or to defer calling them.
>
> Basically, if you're using a power domain, it is assumed that the
> power domain has particular knowledge about the system, and it should
> have the option to override the default behaviour.
>
> >
> > Is the extra overhead of invoking the subsystem callback really all
> > that troublesome?
>
> It isn't an overhead problem. It's a control & complexity problem.
> We could try to implement a heuristic or api to control when the bus
> type PM ops should be overridden, but I think it is cleaner to make it
> a rule that if you implement a power domain, then that power domain
> becomes responsible for all PM operations.
Well said. :-)
I'm taking that as an ACK for my patch if you don't mind.
Thanks,
Rafael
WARNING: multiple messages have this Message-ID (diff)
From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Linux PM mailing list <linux-pm@lists.linux-foundation.org>,
Kevin Hilman <khilman@ti.com>,
LKML <linux-kernel@vger.kernel.org>, Len Brown <lenb@kernel.org>,
linux-sh@vger.kernel.org, lethal@linux-sh.org,
Magnus Damm <magnus.damm@gmail.com>
Subject: Re: [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones
Date: Fri, 15 Apr 2011 01:12:24 +0200 [thread overview]
Message-ID: <201104150112.24722.rjw@sisk.pl> (raw)
In-Reply-To: <BANLkTiknpAkUQMaq3WZSTHy2cs-vXkv08Q@mail.gmail.com>
On Wednesday, April 13, 2011, Grant Likely wrote:
> On Wed, Apr 13, 2011 at 8:17 AM, Alan Stern <stern@rowland.harvard.edu> wrote:
> > On Wed, 13 Apr 2011, Rafael J. Wysocki wrote:
> >
> >> From: Rafael J. Wysocki <rjw@sisk.pl>
> >>
> >> Change the PM core's behavior related to power domains in such a way
> >> that, if a power domain is defined for a given device, its callbacks
> >> will be executed instead of and not in addition to the device
> >> subsystem's PM callbacks.
> >>
> >> The idea behind the initial implementation of power domains handling
> >> by the PM core was that power domain callbacks would be executed in
> >> addition to subsystem callbacks, so that it would be possible to
> >> extend the subsystem callbacks by using power domains. It turns out,
> >> however, that this wouldn't be really convenient in some important
> >> situations.
> >>
> >> For example, there are systems in which power can only be removed
> >> from entire power domains. On those systems it is not desirable to
> >> execute device drivers' PM callbacks until it is known that power is
> >> going to be removed from the devices in question, which means that
> >> they should be executed by power domain callbacks rather then by
> >> subsystem (e.g. bus type) PM callbacks, because subsystems generally
> >> have no information about what devices belong to which power domain.
> >> Thus, for instance, if the bus type in question is the platform bus
> >> type, its PM callbacks generally should not be called in addition to
> >> power domain callbacks, because they run device drivers' callbacks
> >> unconditionally if defined.
> >
> > What about systems where it makes sense to execute the subsystem
> > callbacks even if power isn't going to be removed from the device?
> > It's quite possible that the subsystem could reduce the device's power
> > consumption even when the device isn't powered down completely.
>
> The understanding Rafael and I came to was that if a power domain is
> attached to a device, then the power domain becomes the responsible
> party. Normally this means it will turn around and immediately call
> the bus_type pm ops, but it has the option to not call them if for a
> particular system it knows better, or to defer calling them.
>
> Basically, if you're using a power domain, it is assumed that the
> power domain has particular knowledge about the system, and it should
> have the option to override the default behaviour.
>
> >
> > Is the extra overhead of invoking the subsystem callback really all
> > that troublesome?
>
> It isn't an overhead problem. It's a control & complexity problem.
> We could try to implement a heuristic or api to control when the bus
> type PM ops should be overridden, but I think it is cleaner to make it
> a rule that if you implement a power domain, then that power domain
> becomes responsible for all PM operations.
Well said. :-)
I'm taking that as an ACK for my patch if you don't mind.
Thanks,
Rafael
next prev parent reply other threads:[~2011-04-14 23:12 UTC|newest]
Thread overview: 192+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-13 0:05 [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones Rafael J. Wysocki
2011-04-13 0:05 ` Rafael J. Wysocki
2011-04-13 14:17 ` Alan Stern
2011-04-13 14:17 ` [RFC][PATCH] PM: Make power domain callbacks take precedence Alan Stern
2011-04-13 14:17 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones Alan Stern
2011-04-13 16:15 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over Grant Likely
2011-04-13 16:15 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones Grant Likely
2011-04-14 23:12 ` Rafael J. Wysocki [this message]
2011-04-14 23:12 ` Rafael J. Wysocki
2011-04-15 14:38 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over Grant Likely
2011-04-15 14:38 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones Grant Likely
2011-04-15 14:38 ` Grant Likely
2011-04-15 14:39 ` Alan Stern
2011-04-15 14:39 ` [RFC][PATCH] PM: Make power domain callbacks take precedence Alan Stern
2011-04-15 14:39 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones Alan Stern
2011-04-14 23:12 ` Rafael J. Wysocki
2011-04-13 16:15 ` Grant Likely
2011-04-14 18:20 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over Magnus Damm
2011-04-14 18:20 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones Magnus Damm
2011-04-14 22:45 ` Rafael J. Wysocki
2011-04-14 22:45 ` Rafael J. Wysocki
2011-04-14 22:45 ` Rafael J. Wysocki
2011-04-15 14:34 ` Alan Stern
2011-04-15 14:34 ` [RFC][PATCH] PM: Make power domain callbacks take precedence Alan Stern
2011-04-15 14:34 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones Alan Stern
2011-04-15 23:18 ` Rafael J. Wysocki
2011-04-15 23:18 ` Rafael J. Wysocki
2011-04-15 23:18 ` Rafael J. Wysocki
2011-04-16 17:15 ` [RFC][PATCH] PM: Make power domain callbacks take precedence Kevin Hilman
2011-04-16 17:15 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones Kevin Hilman
2011-04-16 23:12 ` Rafael J. Wysocki
2011-04-16 23:12 ` Rafael J. Wysocki
2011-04-16 23:12 ` Rafael J. Wysocki
2011-04-16 17:15 ` Kevin Hilman
2011-04-14 18:20 ` Magnus Damm
2011-04-14 23:16 ` [RFC][PATCH 0/2] Remove __weak definitions of platform PM callbacks Rafael J. Wysocki
2011-04-14 23:16 ` Rafael J. Wysocki
2011-04-14 23:18 ` [RFC][PATCH 1/2] shmobile: Use power domains for platform runtime PM Rafael J. Wysocki
2011-04-14 23:18 ` Rafael J. Wysocki
2011-04-14 23:18 ` Rafael J. Wysocki
2011-04-14 23:19 ` [RFC][PATCH 2/2] PM / Platform: Use generic runtime PM callbacks directly Rafael J. Wysocki
2011-04-14 23:19 ` Rafael J. Wysocki
2011-04-14 23:19 ` Rafael J. Wysocki
2011-04-14 23:16 ` [RFC][PATCH 0/2] Remove __weak definitions of platform PM callbacks Rafael J. Wysocki
2011-04-16 17:17 ` [RFC][PATCH] PM: Make power domain callbacks take precedence Kevin Hilman
2011-04-16 17:17 ` [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones Kevin Hilman
2011-04-16 17:17 ` Kevin Hilman
2011-04-16 23:35 ` [PATCH 0/9] PM: Rework shmobile and OMAP runtime PM using power domains Rafael J. Wysocki
2011-04-16 23:35 ` Rafael J. Wysocki
2011-04-16 23:35 ` Rafael J. Wysocki
2011-04-16 23:36 ` [PATCH 1/9] PM: Make power domain callbacks take precedence over subsystem ones Rafael J. Wysocki
2011-04-16 23:36 ` Rafael J. Wysocki
2011-04-16 23:36 ` Rafael J. Wysocki
2011-04-16 23:37 ` [PATCH 2/9] PM: Export platform bus type's default PM callbacks Rafael J. Wysocki
2011-04-16 23:37 ` Rafael J. Wysocki
2011-04-16 23:37 ` Rafael J. Wysocki
2011-04-16 23:38 ` [PATCH 3/9] shmobile: Use power domains for platform runtime PM Rafael J. Wysocki
2011-04-16 23:38 ` Rafael J. Wysocki
2011-04-16 23:38 ` Rafael J. Wysocki
2011-04-16 23:38 ` [PATCH 4/9] PM / Platform: Use generic runtime PM callbacks directly Rafael J. Wysocki
2011-04-16 23:38 ` Rafael J. Wysocki
2011-04-16 23:38 ` Rafael J. Wysocki
2011-04-16 23:39 ` [PATCH 5/9] OMAP2+ / PM: Move runtime PM implementation to use power domains Rafael J. Wysocki
2011-04-16 23:39 ` Rafael J. Wysocki
2011-04-16 23:39 ` Rafael J. Wysocki
2011-04-16 23:40 ` [PATCH 6/9] PM / Runtime: Add subsystem data field to struct dev_pm_info Rafael J. Wysocki
2011-04-16 23:40 ` Rafael J. Wysocki
2011-04-16 23:40 ` Rafael J. Wysocki
2011-04-16 23:42 ` [PATCH 7/9] PM / Runtime: Add generic clock manipulation rountines for runtime PM Rafael J. Wysocki
2011-04-16 23:42 ` Rafael J. Wysocki
2011-04-16 23:42 ` Rafael J. Wysocki
2011-04-18 19:59 ` [Update][PATCH " Rafael J. Wysocki
2011-04-18 19:59 ` Rafael J. Wysocki
2011-04-18 19:59 ` Rafael J. Wysocki
2011-04-19 10:18 ` Magnus Damm
2011-04-19 10:18 ` [Update][PATCH 7/9] PM / Runtime: Add generic clock manipulation Magnus Damm
2011-04-19 10:18 ` [Update][PATCH 7/9] PM / Runtime: Add generic clock manipulation rountines for runtime PM Magnus Damm
2011-04-19 21:42 ` Rafael J. Wysocki
2011-04-19 21:42 ` Rafael J. Wysocki
2011-04-19 21:59 ` Paul Mundt
2011-04-19 21:59 ` Paul Mundt
2011-04-19 22:10 ` Rafael J. Wysocki
2011-04-19 22:10 ` Rafael J. Wysocki
2011-04-19 22:10 ` Rafael J. Wysocki
2011-04-19 22:20 ` Paul Mundt
2011-04-19 22:20 ` Paul Mundt
2011-04-19 22:20 ` Paul Mundt
2011-04-19 22:50 ` Rafael J. Wysocki
2011-04-19 22:50 ` Rafael J. Wysocki
2011-04-19 22:50 ` Rafael J. Wysocki
2011-04-19 21:59 ` Paul Mundt
2011-04-19 21:42 ` Rafael J. Wysocki
2011-04-19 10:58 ` [PATCH " Mark Brown
2011-04-19 10:58 ` [linux-pm] [PATCH 7/9] PM / Runtime: Add generic clock Mark Brown
2011-04-19 10:58 ` [linux-pm] [PATCH 7/9] PM / Runtime: Add generic clock manipulation rountines for runtime PM Mark Brown
2011-04-19 21:35 ` Rafael J. Wysocki
2011-04-19 21:35 ` Rafael J. Wysocki
2011-04-20 11:57 ` Mark Brown
2011-04-20 11:57 ` [linux-pm] [PATCH 7/9] PM / Runtime: Add generic clock Mark Brown
2011-04-20 11:57 ` [linux-pm] [PATCH 7/9] PM / Runtime: Add generic clock manipulation rountines for runtime PM Mark Brown
2011-04-19 21:35 ` Rafael J. Wysocki
2011-04-16 23:43 ` [PATCH 8/9] OMAP1 / PM: Use generic clock manipulation routines " Rafael J. Wysocki
2011-04-16 23:43 ` Rafael J. Wysocki
2011-04-18 8:18 ` Paul Mundt
2011-04-18 8:18 ` Paul Mundt
2011-04-18 19:57 ` Rafael J. Wysocki
2011-04-18 19:57 ` Rafael J. Wysocki
2011-04-18 19:57 ` Rafael J. Wysocki
2011-04-18 8:18 ` Paul Mundt
2011-04-16 23:43 ` Rafael J. Wysocki
2011-04-16 23:44 ` [PATCH 9/9] PM: Revert "driver core: platform_bus: allow runtime override of dev_pm_ops" Rafael J. Wysocki
2011-04-16 23:44 ` Rafael J. Wysocki
2011-04-16 23:44 ` Rafael J. Wysocki
2011-04-24 21:30 ` [PATCH 0/9] PM: Rework shmobile and OMAP runtime PM using power domains (v2) Rafael J. Wysocki
2011-04-24 21:30 ` Rafael J. Wysocki
2011-04-24 21:30 ` Rafael J. Wysocki
2011-04-24 21:36 ` [PATCH 1/9] PM: Make power domain callbacks take precedence over subsystem ones Rafael J. Wysocki
2011-04-24 21:36 ` Rafael J. Wysocki
2011-04-24 21:36 ` Rafael J. Wysocki
2011-04-24 21:37 ` [PATCH 2/9] PM: Export platform bus type's default PM callbacks Rafael J. Wysocki
2011-04-24 21:37 ` Rafael J. Wysocki
2011-04-24 21:37 ` Rafael J. Wysocki
2011-04-24 21:38 ` [PATCH 3/9] shmobile: Use power domains for platform runtime PM Rafael J. Wysocki
2011-04-24 21:38 ` Rafael J. Wysocki
2011-04-24 21:38 ` Rafael J. Wysocki
2011-04-24 21:39 ` [PATCH 4/9] PM / Platform: Use generic runtime PM callbacks directly Rafael J. Wysocki
2011-04-24 21:39 ` Rafael J. Wysocki
2011-04-24 21:39 ` Rafael J. Wysocki
2011-04-24 21:41 ` [PATCH 5/9] OMAP2+ / PM: move runtime PM implementation to use device power domains Rafael J. Wysocki
2011-04-24 21:41 ` Rafael J. Wysocki
2011-04-24 21:41 ` Rafael J. Wysocki
2011-04-24 21:42 ` [PATCH 6/9] PM / Runtime: Add subsystem data field to struct dev_pm_info Rafael J. Wysocki
2011-04-24 21:42 ` Rafael J. Wysocki
2011-04-24 21:42 ` Rafael J. Wysocki
2011-04-24 21:42 ` [PATCH 7/9] PM / Runtime: Generic clock manipulation rountines for runtime PM (v2) Rafael J. Wysocki
2011-04-24 21:42 ` Rafael J. Wysocki
2011-04-24 21:42 ` Rafael J. Wysocki
2011-04-27 21:48 ` [Update][PATCH 7/9] PM / Runtime: Generic clock manipulation rountines for runtime PM (v3) Rafael J. Wysocki
2011-04-27 21:48 ` Rafael J. Wysocki
2011-04-27 21:48 ` Rafael J. Wysocki
2011-04-27 23:04 ` [Update][PATCH 7/9] PM / Runtime: Generic clock manipulation Colin Cross
2011-04-27 23:04 ` [Update][PATCH 7/9] PM / Runtime: Generic clock manipulation rountines for runtime PM (v3) Colin Cross
2011-04-28 0:58 ` Rafael J. Wysocki
2011-04-28 0:58 ` Rafael J. Wysocki
2011-04-28 0:58 ` Rafael J. Wysocki
2011-04-28 1:06 ` Rafael J. Wysocki
2011-04-28 1:06 ` Rafael J. Wysocki
2011-04-28 1:33 ` Rafael J. Wysocki
2011-04-28 1:33 ` Rafael J. Wysocki
2011-04-28 1:33 ` Rafael J. Wysocki
2011-04-28 19:36 ` [Update x2][PATCH 7/9] PM / Runtime: Generic clock manipulation rountines for runtime PM (v5) Rafael J. Wysocki
2011-04-28 19:36 ` Rafael J. Wysocki
2011-04-29 19:35 ` Stephen Boyd
2011-04-29 19:35 ` [Update x2][PATCH 7/9] PM / Runtime: Generic clock manipulation Stephen Boyd
2011-04-29 19:35 ` [Update x2][PATCH 7/9] PM / Runtime: Generic clock manipulation rountines for runtime PM (v5) Stephen Boyd
2011-04-29 20:29 ` Rafael J. Wysocki
2011-04-29 20:29 ` Rafael J. Wysocki
2011-04-29 22:04 ` [Update x3][PATCH 7/9] PM / Runtime: Generic clock manipulation rountines for runtime PM (v6) Rafael J. Wysocki
2011-04-29 22:04 ` Rafael J. Wysocki
2011-04-29 22:04 ` Rafael J. Wysocki
2011-05-03 17:00 ` Stephen Boyd
2011-05-03 17:00 ` [Update x3][PATCH 7/9] PM / Runtime: Generic clock manipulation Stephen Boyd
2011-05-03 17:00 ` [Update x3][PATCH 7/9] PM / Runtime: Generic clock manipulation rountines for runtime PM (v6) Stephen Boyd
2011-05-03 17:38 ` Rafael J. Wysocki
2011-05-03 17:38 ` Rafael J. Wysocki
2011-05-03 17:38 ` Rafael J. Wysocki
2011-04-29 20:29 ` [Update x2][PATCH 7/9] PM / Runtime: Generic clock manipulation rountines for runtime PM (v5) Rafael J. Wysocki
2011-04-28 19:36 ` Rafael J. Wysocki
2011-04-28 1:06 ` [Update][PATCH 7/9] PM / Runtime: Generic clock manipulation rountines for runtime PM (v3) Rafael J. Wysocki
2011-04-29 20:50 ` Grant Likely
2011-04-29 20:50 ` [Update][PATCH 7/9] PM / Runtime: Generic clock manipulation Grant Likely
2011-04-29 20:50 ` [Update][PATCH 7/9] PM / Runtime: Generic clock manipulation rountines for runtime PM (v3) Grant Likely
2011-04-29 21:07 ` Rafael J. Wysocki
2011-04-29 21:07 ` Rafael J. Wysocki
2011-04-29 21:07 ` Rafael J. Wysocki
2011-04-27 23:04 ` Colin Cross
2011-04-24 21:43 ` [PATCH 8/9] OMAP1 / PM: Use generic clock manipulation routines for runtime PM Rafael J. Wysocki
2011-04-24 21:43 ` Rafael J. Wysocki
2011-05-16 10:16 ` Kevin Hilman
2011-05-16 10:16 ` Kevin Hilman
2011-05-16 18:26 ` Rafael J. Wysocki
2011-05-16 18:26 ` Rafael J. Wysocki
2011-05-16 18:26 ` Rafael J. Wysocki
2011-05-16 10:16 ` Kevin Hilman
2011-04-24 21:43 ` Rafael J. Wysocki
2011-04-24 21:44 ` [PATCH 9/9] PM: Revert "driver core: platform_bus: allow runtime override of dev_pm_ops" Rafael J. Wysocki
2011-04-24 21:44 ` Rafael J. Wysocki
2011-04-24 21:44 ` Rafael J. Wysocki
2011-04-24 23:36 ` [PATCH 0/9] PM: Rework shmobile and OMAP runtime PM using power domains (v2) Greg KH
2011-04-24 23:36 ` [PATCH 0/9] PM: Rework shmobile and OMAP runtime PM using power Greg KH
2011-04-24 23:36 ` [PATCH 0/9] PM: Rework shmobile and OMAP runtime PM using power domains (v2) Greg KH
2011-04-13 0:05 [RFC][PATCH] PM: Make power domain callbacks take precedence over subsystem ones Rafael J. Wysocki
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