From: Huang Ying <ying.huang@intel.com>
To: Alan Stern <stern@rowland.harvard.edu>
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: Mon, 12 Nov 2012 13:55:44 +0800 [thread overview]
Message-ID: <1352699744.7176.169.camel@yhuang-dev> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1211112131500.16611-100000@netrider.rowland.org>
On Sun, 2012-11-11 at 21:36 -0500, Alan Stern wrote:
> On Mon, 12 Nov 2012, Huang Ying wrote:
>
> > > The first question: How should the PCI subsystem prevent the parents of
> > > driverless VGA devices from being runtime suspended while userspace is
> > > accessing them?
> >
> > I think Rafael's patch is good for that.
>
> But his patch isn't needed if we make these other changes.
Yes.
> > > 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?
> >
> > I think that should not be allowed.
>
> Disallowing it is okay with me too. But it will require several
> changes to the code, more than what your patch did.
Yes. I think so too.
> > > 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?
> >
> > Is it absolute necessary to call pm_runtime_set_suspended? If the
> > device is disabled, the transition to SUSPENDED state will not be
> > triggered even if the device is ACTIVE.
>
> It's not absolutely necessary to do this, but we ought to because it
> will allow the device's parent to be suspended. If we leave the device
> in the ACTIVE state then the parent can't be suspended, even when the
> device is disabled.
I think this is the hard part of the issue. Now "disabled" and
SUSPENDED state is managed by hand. IMHO, if we changed
pm_runtime_allow() as you said, we need to change the rule too. Maybe
something as follow:
- remove pm_runtime_set_suspended/pm_runtime_set_active
- in pm_runtime_disable/pm_runtime_allow, put device into SUSPENDED
state if runtime PM is not forbidden.
- in pm_runtime_forbid/pm_runtime_enable, put device into ACTIVE state.
Best Regards,
Huang Ying
next prev parent reply other threads:[~2012-11-12 5:55 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
2012-11-12 0:37 ` Huang Ying
2012-11-12 2:36 ` Alan Stern
2012-11-12 5:55 ` Huang Ying [this message]
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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