linux-kernel - Re: [PATCH] PM / Sleep: Simplify generic system suspend callbacks

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Date:	Sat, 10 Dec 2011 00:05:24 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Linux PM list <linux-pm@...r.kernel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PM / Sleep: Simplify generic system suspend callbacks

On Sunday, November 27, 2011, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@...k.pl>
> 
> The pm_runtime_suspended() check in __pm_generic_call() doesn't
> really help and may cause problems to happen, because in some cases
> the system suspend callbacks need to be called even if the given
> device has been suspended by runtime PM.  For example, if the device
> generally supports remote wakeup and is not enabled to wake up
> the system from sleep, it should be prevented from generating wakeup
> signals during system suspend and that has to be done by the
> suspend callbacks that the pm_runtime_suspended() check prevents from
> being executed.
> 
> Similarly, it may not be a good idea to unconditionally change
> the runtime PM status of the device to 'active' in
> __pm_generic_resume(), because the driver may want to leave the
> device in the 'suspended' state, depending on what happened to it
> before the system suspend and whether or not it is enabled to
> wake up the system.
> 
> For the above reasons, remove the pm_runtime_suspended()
> check from __pm_generic_call() and remove the code changing the
> device's runtime PM status from __pm_generic_resume().
> 
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>

Well, I'm not seeing any objections, so I gather so this change is fine
by everyone.  I'm going to put it into linux-pm/linux-next, then.

Thanks,
Rafael


> ---
>  drivers/base/power/generic_ops.c |   15 ++-------------
>  1 file changed, 2 insertions(+), 13 deletions(-)
> 
> Index: linux/drivers/base/power/generic_ops.c
> ===================================================================
> --- linux.orig/drivers/base/power/generic_ops.c
> +++ linux/drivers/base/power/generic_ops.c
> @@ -106,7 +106,7 @@ static int __pm_generic_call(struct devi
>  	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
>  	int (*callback)(struct device *);
>  
> -	if (!pm || pm_runtime_suspended(dev))
> +	if (!pm)
>  		return 0;
>  
>  	switch (event) {
> @@ -224,7 +224,6 @@ static int __pm_generic_resume(struct de
>  {
>  	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
>  	int (*callback)(struct device *);
> -	int ret;
>  
>  	if (!pm)
>  		return 0;
> @@ -241,17 +240,7 @@ static int __pm_generic_resume(struct de
>  		break;
>  	}
>  
> -	if (!callback)
> -		return 0;
> -
> -	ret = callback(dev);
> -	if (!ret && !noirq && pm_runtime_enabled(dev)) {
> -		pm_runtime_disable(dev);
> -		pm_runtime_set_active(dev);
> -		pm_runtime_enable(dev);
> -	}
> -
> -	return ret;
> +	return callback ? callback(dev) : 0;
>  }
>  
>  /**
> 
> --
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> 

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