linux-kernel - Re: [PATCH v8 1/5] PM / Runtime: Add getter for querying the IRQ safe option

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Message-ID: <32933431.rIxraemF7M@vostro.rjw.lan>
Date:	Sat, 01 Nov 2014 00:11:05 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	Pavel Machek <pavel@....cz>, Russell King <linux@....linux.org.uk>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Alan Stern <stern@...land.harvard.edu>,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Kevin Hilman <khilman@...nel.org>
Subject: Re: [PATCH v8 1/5] PM / Runtime: Add getter for querying the IRQ safe option

[CC list trimmed + added Kevin Hilman]

On Monday, October 20, 2014 11:04:44 AM Krzysztof Kozlowski wrote:
> Add a simple getter pm_runtime_is_irq_safe() for querying whether runtime
> PM IRQ safe was set or not.
> 
> Various bus drivers implementing runtime PM may use choose to suspend
> differently based on IRQ safeness status of child driver (e.g. do not
> unprepare the clock if IRQ safe is not set).
> 
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>

So why do we need to add the wrapper?

And it goes kind of against the intention which was to set irq_safe when
we knew that the callbacks were safe to be executed from interrupt context
and not when we wished that to be the case.

> ---
>  Documentation/power/runtime_pm.txt | 4 ++++
>  include/linux/pm_runtime.h         | 6 ++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
> index f32ce5419573..397b81593142 100644
> --- a/Documentation/power/runtime_pm.txt
> +++ b/Documentation/power/runtime_pm.txt
> @@ -468,6 +468,10 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
>      - set the power.irq_safe flag for the device, causing the runtime-PM
>        callbacks to be invoked with interrupts off
>  
> +  bool pm_runtime_is_irq_safe(struct device *dev);
> +    - return true if power.irq_safe flag was set for the device, causing
> +      the runtime-PM callbacks to be invoked with interrupts off
> +
>    void pm_runtime_mark_last_busy(struct device *dev);
>      - set the power.last_busy field to the current time
>  
> diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
> index 367f49b9a1c9..44d74f0f182e 100644
> --- a/include/linux/pm_runtime.h
> +++ b/include/linux/pm_runtime.h
> @@ -128,6 +128,11 @@ static inline void pm_runtime_mark_last_busy(struct device *dev)
>  	ACCESS_ONCE(dev->power.last_busy) = jiffies;
>  }
>  
> +static inline bool pm_runtime_is_irq_safe(struct device *dev)
> +{
> +	return dev->power.irq_safe;
> +}
> +
>  #else /* !CONFIG_PM_RUNTIME */
>  
>  static inline int __pm_runtime_idle(struct device *dev, int rpmflags)
> @@ -167,6 +172,7 @@ static inline bool pm_runtime_enabled(struct device *dev) { return false; }
>  
>  static inline void pm_runtime_no_callbacks(struct device *dev) {}
>  static inline void pm_runtime_irq_safe(struct device *dev) {}
> +static inline bool pm_runtime_is_irq_safe(struct device *dev) { return false; }
>  
>  static inline bool pm_runtime_callbacks_present(struct device *dev) { return false; }
>  static inline void pm_runtime_mark_last_busy(struct device *dev) {}
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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