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Message-ID: <Pine.LNX.4.44L0.0906221222490.15425-100000@iolanthe.rowland.org>
Date: Mon, 22 Jun 2009 12:28:14 -0400 (EDT)
From: Alan Stern <stern@...land.harvard.edu>
To: "Rafael J. Wysocki" <rjw@...k.pl>
cc: Oliver Neukum <oliver@...kum.org>,
Magnus Damm <magnus.damm@...il.com>,
<linux-pm@...ts.linux-foundation.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Ingo Molnar <mingo@...e.hu>,
LKML <linux-kernel@...r.kernel.org>, Greg KH <gregkh@...e.de>
Subject: Re: [patch update 3] PM: Introduce core framework for run-time PM
of I/O devices
On Mon, 22 Jun 2009, Rafael J. Wysocki wrote:
> > Again, this boils down to how drivers decide to use the async
> > interface. I can see justifications for both pm_request_resume_get
> > (which would always increment the counter) and pm_request_resume (which
> > would increment the counter only if a work item had to be queued).
>
> OK, so this means we should provide both at the core level and let the drivers
> decide which one to use.
>
> I think in both cases the caller would be responsible for decrementing the
> counter?
Sure. They could call pm_runtime_put just once at the end of their
runtime_resume method (assuming they used pm_request_resume), or they
could call it at every place where some deferred work was finished
(assuming they used pm_request_resume_get).
> > Okay, we don't need it then. I forgot to mention in the previous
> > message that there also has to be a pm_runtime_del() routine, which
> > should cancel pending workqueue items and set the counter to some high
> > value so that no new items are added.
>
> Should that be called by device_pm_remove()? I think so.
Yes. I suppose it could be named pm_runtime_remove. Either would be
okay.
Alan Stern
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