From: Alan Stern <stern@rowland.harvard.edu>
To: Huang Ying <ying.huang@intel.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, <linux-kernel@vger.kernel.org>,
<linux-pm@vger.kernel.org>
Subject: Re: [BUGFIX] PM: Fix active child counting when disabled and forbidden
Date: Fri, 9 Nov 2012 11:41:51 -0500 (EST) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1211091131190.1702-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <1352428604.7176.103.camel@yhuang-dev>
On Fri, 9 Nov 2012, Huang Ying wrote:
> On Thu, 2012-11-08 at 12:07 -0500, Alan Stern wrote:
> > On Thu, 8 Nov 2012, Rafael J. Wysocki wrote:
> >
> > > > > > is it a good idea to allow to set device state to SUSPENDED if the device
> > > > > > is disabled?
> > > > >
> > > > > No, it is not. The status should always be ACTIVE as long as usage_count > 0.
> >
> > That isn't strictly true, because pm_runtime_get_noresume violates this
> > rule. What the PM core actually does is prevent a transition from the
> > ACTIVE state to the SUSPENDING/SUSPENDED state if usage_count > 0,
> > _provided_ runtime PM is enabled. There's no such restriction when it
> > is disabled.
>
> Usage count may be not a issue for the end user. But "on" in "control"
> sysfs file + SUSPENDED can be confusing for the end user. Maybe we need
> to check dev->power.runtime_auto in pm_runtime_set_suspended().
You are confusing the issue by raising two separate (though related)
questions.
The first question: How should the PCI subsystem prevent the parents of
driverless VGA devices from being runtime suspended while userspace is
accessing them?
The second question: Should the PM core allow devices that are disabled
for runtime PM to be in the SUSPENDED state when
dev->power.runtime_auto is clear?
Assuming we don't want to allow this, there's a third question: Should
pm_runtime_allow call pm_runtime_set_suspended if the device is
disabled?
Alan Stern
next prev parent reply other threads:[~2012-11-09 16:41 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-05 1:17 [BUGFIX] PM: Fix active child counting when disabled and forbidden Huang Ying
2012-11-05 1:56 ` Alan Stern
2012-11-06 0:43 ` Huang Ying
2012-11-06 15:17 ` Alan Stern
2012-11-07 0:26 ` Huang Ying
2012-11-07 15:49 ` Alan Stern
2012-11-07 16:09 ` Rafael J. Wysocki
2012-11-07 17:17 ` Alan Stern
2012-11-07 20:21 ` Rafael J. Wysocki
2012-11-07 20:47 ` Alan Stern
2012-11-07 21:44 ` Rafael J. Wysocki
2012-11-07 21:56 ` Alan Stern
2012-11-07 22:51 ` Rafael J. Wysocki
2012-11-07 23:09 ` Rafael J. Wysocki
2012-11-08 1:15 ` Huang Ying
2012-11-08 1:35 ` Rafael J. Wysocki
2012-11-08 2:04 ` Huang Ying
2012-11-08 9:56 ` Rafael J. Wysocki
2012-11-08 17:07 ` Alan Stern
2012-11-09 2:36 ` Huang Ying
2012-11-09 16:41 ` Alan Stern [this message]
2012-11-12 0:37 ` Huang Ying
2012-11-12 2:36 ` Alan Stern
2012-11-12 5:55 ` Huang Ying
2012-11-12 16:32 ` Alan Stern
2012-11-13 1:19 ` Huang Ying
2012-11-13 2:32 ` Alan Stern
2012-11-13 5:12 ` Huang Ying
2012-11-13 16:10 ` Alan Stern
2012-11-14 1:08 ` Huang Ying
2012-11-14 9:52 ` Rafael J. Wysocki
2012-11-14 13:35 ` Huang Ying
2012-11-14 16:06 ` Alan Stern
2012-11-13 23:43 ` Rafael J. Wysocki
2012-11-14 10:05 ` Rafael J. Wysocki
2012-11-14 16:42 ` Alan Stern
2012-11-14 19:42 ` Rafael J. Wysocki
2012-11-14 21:45 ` Alan Stern
2012-11-14 23:10 ` Rafael J. Wysocki
2012-11-15 1:03 ` Huang Ying
2012-11-15 9:51 ` Rafael J. Wysocki
2012-11-15 10:09 ` Rafael J. Wysocki
2012-11-15 15:27 ` Alan Stern
2012-11-16 0:36 ` Huang Ying
2012-11-16 0:44 ` Rafael J. Wysocki
2012-11-16 0:48 ` Huang Ying
2012-11-16 0:55 ` Rafael J. Wysocki
2012-11-16 0:54 ` Huang Ying
2012-11-16 1:29 ` Rafael J. Wysocki
2012-11-16 1:27 ` Huang Ying
2012-11-16 10:10 ` Rafael J. Wysocki
2012-11-16 3:11 ` Huang Ying
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