On 14 December 2015 at 23:22, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> Introduce a new runtime PM function, pm_runtime_get_if_in_use(),
As we already have pm_runtime_set_active() and pm_runtime_active(),
changing the new function name to "pm_runtime_get_if_active" may be
better!?
> 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@xxxxxxxxx>
> Acked-by: Imre Deak <imre.deak@xxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> 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);
Don't we also need to check that runtime PM is enabled (&&
!dev->power.disable_depth), or the user of this function don't care
about that?
> + spin_unlock_irqrestore(&dev->power.lock, flags);
> + return retval;
> +}
> +EXPORT_SYMBOL_GPL(pm_runtime_get_if_in_use);
> +
[...]
Kind regards
Uffe
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