[Intel-gfx] [PATCH] PM / runtime: Add new helper for conditional usage count incrementation

[Joonas Lahtinen]

On ma, 2015-12-14 at 23:22 +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
> 
> Introduce a new runtime PM function, pm_runtime_get_if_in_use(),
> that will increment the device's runtime PM usage counter and
> return 'true' if its status is RPM_ACTIVE and its usage counter
> is greater than 0 at the same time ('false' will be returned
> otherwise).
> 
> This is useful for things that should only be done if the device
> is active (from the runtime PM perspective) and used by somebody
> (as indicated by the usage counter) already and they are not worth
> bothering otherwise.
> 
> Requested-by: Imre Deak <imre.deak at intel.com>
> Acked-by: Imre Deak <imre.deak at intel.com>

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
> ---
>  Documentation/power/runtime_pm.txt |    5 +++++
>  drivers/base/power/runtime.c       |   21 +++++++++++++++++++++
>  include/linux/pm_runtime.h         |    5 +++++
>  3 files changed, 31 insertions(+)
> 
> Index: linux-pm/drivers/base/power/runtime.c
> ===================================================================
> --- linux-pm.orig/drivers/base/power/runtime.c
> +++ linux-pm/drivers/base/power/runtime.c
> @@ -966,6 +966,27 @@ int __pm_runtime_resume(struct device *d
>  EXPORT_SYMBOL_GPL(__pm_runtime_resume);
>  
>  /**
> + * pm_runtime_get_if_in_use - Conditionally bump up the device's
> usage counter.
> + * @dev: Device to handle.
> + *
> + * Increment the device's runtime PM usage counter and return 'true'
> if its
> + * runtime PM status is RPM_ACTIVE and its usage counter is already
> different
> + * from zero at the same time.  Otherwise, return 'false'.
> + */
> +bool pm_runtime_get_if_in_use(struct device *dev)
> +{
> +	unsigned long flags;
> +	bool retval;
> +
> +	spin_lock_irqsave(&dev->power.lock, flags);
> +	retval = dev->power.runtime_status == RPM_ACTIVE
> +		&& atomic_inc_not_zero(&dev->power.usage_count);
> +	spin_unlock_irqrestore(&dev->power.lock, flags);
> +	return retval;
> +}
> +EXPORT_SYMBOL_GPL(pm_runtime_get_if_in_use);
> +
> +/**
>   * __pm_runtime_set_status - Set runtime PM status of a device.
>   * @dev: Device to handle.
>   * @status: New runtime PM status of the device.
> Index: linux-pm/include/linux/pm_runtime.h
> ===================================================================
> --- linux-pm.orig/include/linux/pm_runtime.h
> +++ linux-pm/include/linux/pm_runtime.h
> @@ -39,6 +39,7 @@ extern int pm_runtime_force_resume(struc
>  extern int __pm_runtime_idle(struct device *dev, int rpmflags);
>  extern int __pm_runtime_suspend(struct device *dev, int rpmflags);
>  extern int __pm_runtime_resume(struct device *dev, int rpmflags);
> +extern bool pm_runtime_get_if_in_use(struct device *dev);
>  extern int pm_schedule_suspend(struct device *dev, unsigned int
> delay);
>  extern int __pm_runtime_set_status(struct device *dev, unsigned int
> status);
>  extern int pm_runtime_barrier(struct device *dev);
> @@ -143,6 +144,10 @@ static inline int pm_schedule_suspend(st
>  {
>  	return -ENOSYS;
>  }
> +static inline bool pm_runtime_get_if_in_use(struct device *dev)
> +{
> +	return true;
> +}
>  static inline int __pm_runtime_set_status(struct device *dev,
>  					    unsigned int status) {
> return 0; }
>  static inline int pm_runtime_barrier(struct device *dev) { return 0;
> }
> Index: linux-pm/Documentation/power/runtime_pm.txt
> ===================================================================
> --- linux-pm.orig/Documentation/power/runtime_pm.txt
> +++ linux-pm/Documentation/power/runtime_pm.txt
> @@ -371,6 +371,11 @@ drivers/base/power/runtime.c and include
>      - increment the device's usage counter, run
> pm_runtime_resume(dev) and
>        return its result
>  
> +  bool pm_runtime_get_if_in_use(struct device *dev);
> +    - increment the device's usage counter and return 'true' if its
> runtime PM
> +      status is 'active' and its usage counter is greater than 0 at
> the same
> +      time; return 'false' otherwise
> +
>    void pm_runtime_put_noidle(struct device *dev);
>      - decrement the device's usage counter
>  
> 
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation