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In-Reply-To: <201011281312.49949.rjw@sisk.pl>
References: <201011281312.49949.rjw@sisk.pl>
Date: Tue, 30 Nov 2010 21:07:58 +0800
Message-ID: <AANLkTi=tgEug5EUpqV1-GLFh9rsD5obAyExe+V=CjsbO@mail.gmail.com>
Subject: Re: [PATCH] PM: Prevent dpm_prepare() from returning errors unnecessarily
From: Ming Lei <tom.leiming@gmail.com>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Linux-pm mailing list <linux-pm@lists.linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Alan Stern <stern@rowland.harvard.edu>
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2010/11/28 Rafael J. Wysocki <rjw@sisk.pl>:
> From: Rafael J. Wysocki <rjw@sisk.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@sisk.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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