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Message-ID: <Pine.LNX.4.44L0.1505141409060.1107-100000@iolanthe.rowland.org>
Date: Thu, 14 May 2015 14:12:59 -0400 (EDT)
From: Alan Stern <stern@...land.harvard.edu>
To: Tomeu Vizoso <tomeu.vizoso@...labora.com>
cc: linux-pm@...r.kernel.org,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
Kevin Hilman <khilman@...nel.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] PM / sleep: Let devices force direct_complete
On Thu, 14 May 2015, Tomeu Vizoso wrote:
> Introduce a new per-device flag power.force_direct_complete that will
> instruct the PM core to let that device remain in runtime suspend when
> the system goes into a sleep power state, regardless of the PM state of
> any of its descendants.
>
> This is needed because otherwise it would be needed to get dozens of
> drivers to implement the prepare() callback and be runtime PM active
> even if they don't have a 1-to-1 relationship with a piece of HW.
>
> This only applies to devices that aren't wakeup-capable, as those would
> need to setup their IRQs as wakeup-capable in their prepare() callbacks.
>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
There's one little problem in this...
> @@ -1605,9 +1607,13 @@ static int device_prepare(struct device *dev, pm_message_t state)
> * will do the same thing with all of its descendants". This only
> * applies to suspend transitions, however.
> */
> - spin_lock_irq(&dev->power.lock);
> - dev->power.direct_complete = ret > 0 && state.event == PM_EVENT_SUSPEND;
> - spin_unlock_irq(&dev->power.lock);
> + if (state.event == PM_EVENT_SUSPEND) {
> + spin_lock_irq(&dev->power.lock);
> + dev->power.direct_complete = ret > 0 ||
> + (dev->power.force_direct_complete &&
> + !device_can_wakeup(dev));
> + spin_unlock_irq(&dev->power.lock);
> + }
When state.event is not PM_EVENT_SUSPEND, this fails to set
dev->power.direct_complete to 0. Sticking closer to the original code
arrangement would help.
Aside from that small issue:
Acked-by: Alan Stern <stern@...land.harvard.edu>
Alan Stern
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