linux-kernel - Re: [PATCH] PM: Prevent dpm_prepare() from returning errors unnecessarily

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Date:	Tue, 30 Nov 2010 21:07:58 +0800
From:	Ming Lei <tom.leiming@...il.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Linux-pm mailing list <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Alan Stern <stern@...land.harvard.edu>
Subject: Re: [PATCH] PM: Prevent dpm_prepare() from returning errors unnecessarily

2010/11/28 Rafael J. Wysocki <rjw@...k.pl>:
> From: Rafael J. Wysocki <rjw@...k.pl>
>
> Currently dpm_prepare() returns error code if it finds that a device
> being suspended has a pending runtime resume request.  However, it
> should not do that if the checking for wakeup events is not enabled.
> On the other hand, if the checking for wakeup events is enabled, it
> can return error when a wakeup event is detected, regardless of its
> source.
>
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> ---
>  drivers/base/power/main.c |   11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> Index: linux-2.6/drivers/base/power/main.c
> ===================================================================
> --- linux-2.6.orig/drivers/base/power/main.c
> +++ linux-2.6/drivers/base/power/main.c
> @@ -26,6 +26,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/sched.h>
>  #include <linux/async.h>
> +#include <linux/suspend.h>
>
>  #include "../base.h"
>  #include "power.h"
> @@ -1052,8 +1053,10 @@ static int dpm_prepare(pm_message_t stat
>                mutex_unlock(&dpm_list_mtx);
>
>                pm_runtime_get_noresume(dev);
> -               if (pm_runtime_barrier(dev) && device_may_wakeup(dev)) {
> -                       /* Wake-up requested during system sleep transition. */
> +               if (pm_runtime_barrier(dev) && device_may_wakeup(dev))
> +                       pm_wakeup_event(dev, 0);
> +
> +               if (pm_check_wakeup_events()) {

If pm_check_wakeup_events returns true, it means there is no wakeup event
coming, so seems should handle normal suspend prepare, but why
abort the suspend here?

>                        pm_runtime_put_sync(dev);
>                        error = -EBUSY;
>                } else {



thanks,
-- 
Lei Ming
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