From: Alan Stern <stern@rowland.harvard.edu>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Greg KH <gregkh@suse.de>,
linux-pci@vger.kernel.org, linux-usb@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
Linux-pm mailing list <linux-pm@lists.linux-foundation.org>
Subject: Re: [RFC] PCI: Runtime power management
Date: Sat, 15 Aug 2009 11:53:27 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.0908151143560.18415-100000__23491.0022969872$1250351666$gmane$org@netrider.rowland.org> (raw)
In-Reply-To: <200908151618.10169.rjw@sisk.pl>
On Sat, 15 Aug 2009, Rafael J. Wysocki wrote:
> > > Why don't we add a flag indicating whether or not the device is allowed to
> > > be power managed at run time, something like runtime_forbidden, that the
> > > user space will be able to set through sysfs?
> >
> > I think even having a runtime_wakeup flag (which defaults to on) would
> > be sufficient.
>
> Perhaps it would, but then unsetting runtime_wakeup would effectively disable
> runtime PM for devices that need it to be power managed at run time (probably
> all input devices). Also there may be situations in which user space may
> really want to disable runtime PM for some devices (think of broken hardware
> for one example).
It sounds like there are really three choices here, and the decision
should largely be left up to the user:
1. don't use runtime PM,
2. allow runtime PM but disable remote wakeup,
3. allow runtime PM with remote wakeup enabled.
Now, a driver may say "I can't do my job without remote wakeup". Such
a driver would refuse to do runtime_suspend in case 2. But otherwise
we should follow the preference of the user.
The only remaining question is how to expose this in sysfs in a way
that won't be confusing and that won't be confused with the "wakeup"
attribute. One possibility is to use the "level" attribute introduced
in USB; possible levels are "on" (no runtime PM) and "auto" (runtime
PM allowed). Then a new "runtime_wakeup" attribute could contain
nothing (if wakeup is not available), "enabled", or "disabled".
Alan Stern
next prev parent reply other threads:[~2009-08-15 15:53 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-08 14:25 [PATCH] PM: Introduce core framework for run-time PM of I/O devices (rev. 14) Rafael J. Wysocki
2009-08-09 21:13 ` [PATCH update] PM: Introduce core framework for run-time PM of I/O devices (rev. 15) Rafael J. Wysocki
2009-08-09 21:13 ` Rafael J. Wysocki
2009-08-12 10:37 ` Magnus Damm
2009-08-12 15:47 ` Alan Stern
2009-08-12 15:47 ` Alan Stern
2009-08-12 20:13 ` Rafael J. Wysocki
2009-08-12 20:13 ` Rafael J. Wysocki
2009-08-12 10:37 ` Magnus Damm
2009-08-13 0:29 ` [RFC] PCI: Runtime power management Matthew Garrett
2009-08-13 0:29 ` Matthew Garrett
2009-08-13 0:35 ` [RFC] usb: Add support for runtime power management of the hcd Matthew Garrett
2009-08-13 12:16 ` Oliver Neukum
2009-08-13 12:16 ` [linux-pm] " Oliver Neukum
2009-08-13 12:30 ` Matthew Garrett
2009-08-13 12:30 ` [linux-pm] " Matthew Garrett
2009-08-13 14:26 ` Oliver Neukum
2009-08-13 14:26 ` [linux-pm] " Oliver Neukum
2009-08-13 21:42 ` Matthew Garrett
2009-08-13 21:42 ` Matthew Garrett
2009-08-13 15:22 ` Alan Stern
2009-08-13 15:22 ` Alan Stern
2009-08-13 21:47 ` Matthew Garrett
2009-08-13 21:47 ` Matthew Garrett
2009-08-13 0:35 ` Matthew Garrett
2009-08-13 15:17 ` [RFC] PCI: Runtime power management Alan Stern
2009-08-13 21:47 ` Matthew Garrett
2009-08-14 12:30 ` Matthew Garrett
2009-08-14 12:30 ` [linux-pm] " Matthew Garrett
2009-08-14 14:43 ` Alan Stern
2009-08-14 14:43 ` [linux-pm] " Alan Stern
2009-08-14 17:05 ` Rafael J. Wysocki
2009-08-14 17:05 ` [linux-pm] " Rafael J. Wysocki
2009-08-14 17:13 ` Rafael J. Wysocki
2009-08-14 17:13 ` [linux-pm] " Rafael J. Wysocki
2009-08-14 19:01 ` Alan Stern
2009-08-14 19:01 ` Alan Stern
2009-08-14 20:05 ` [linux-pm] " Rafael J. Wysocki
2009-08-14 22:21 ` Matthew Garrett
2009-08-15 14:18 ` Rafael J. Wysocki
2009-08-15 14:18 ` [linux-pm] " Rafael J. Wysocki
2009-08-15 15:53 ` Alan Stern [this message]
2009-08-15 15:53 ` Alan Stern
2009-08-15 20:54 ` Rafael J. Wysocki
2009-08-15 20:54 ` [linux-pm] " Rafael J. Wysocki
2009-08-15 20:58 ` Matthew Garrett
2009-08-15 20:58 ` [linux-pm] " Matthew Garrett
2009-08-15 21:21 ` Rafael J. Wysocki
2009-08-15 21:21 ` Rafael J. Wysocki
2009-08-15 21:27 ` [linux-pm] " Matthew Garrett
2009-08-15 21:44 ` Rafael J. Wysocki
2009-08-15 21:44 ` [linux-pm] " Rafael J. Wysocki
2009-08-16 16:09 ` Alan Stern
2009-08-16 16:09 ` Alan Stern
2009-08-15 21:27 ` Matthew Garrett
2009-08-16 15:57 ` Alan Stern
2009-08-16 15:57 ` [linux-pm] " Alan Stern
2009-08-16 16:04 ` Matthew Garrett
2009-08-16 16:04 ` [linux-pm] " Matthew Garrett
2009-08-16 15:50 ` Alan Stern
2009-08-16 15:50 ` [linux-pm] " Alan Stern
2009-08-14 22:21 ` Matthew Garrett
2009-08-14 20:05 ` Rafael J. Wysocki
2009-08-13 21:47 ` Matthew Garrett
2009-08-13 15:17 ` Alan Stern
2009-08-14 17:37 ` Jesse Barnes
2009-08-14 17:37 ` Jesse Barnes
2009-08-14 19:15 ` Rafael J. Wysocki
2009-08-14 19:15 ` Rafael J. Wysocki
2009-08-14 21:22 ` Rafael J. Wysocki
2009-08-14 22:30 ` Matthew Garrett
2009-08-14 22:30 ` Matthew Garrett
2009-08-15 14:41 ` Rafael J. Wysocki
2009-08-15 15:24 ` Rafael J. Wysocki
2009-08-15 15:24 ` Rafael J. Wysocki
2009-08-15 14:41 ` Rafael J. Wysocki
2009-08-14 21:22 ` Rafael J. Wysocki
2009-08-13 20:56 ` [PATCH update 2x] PM: Introduce core framework for run-time PM of I/O devices (rev. 16) Rafael J. Wysocki
2009-08-13 21:03 ` Paul Mundt
2009-08-13 21:03 ` Paul Mundt
2009-08-13 21:14 ` Rafael J. Wysocki
2009-08-13 21:14 ` Rafael J. Wysocki
2009-08-14 9:08 ` Magnus Damm
2009-08-14 17:19 ` Rafael J. Wysocki
2009-08-14 17:19 ` Rafael J. Wysocki
2009-08-14 9:08 ` Magnus Damm
2009-08-14 17:25 ` [PATCH update 3x] PM: Introduce core framework for run-time PM of I/O devices (rev. 17) Rafael J. Wysocki
2009-08-14 17:25 ` Rafael J. Wysocki
2009-08-13 20:56 ` [PATCH update 2x] PM: Introduce core framework for run-time PM of I/O devices (rev. 16) Rafael J. Wysocki
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