On Monday, November 25, 2013 01:40:21 PM Ulf Hansson wrote:
> To put devices into low power state during sleep, it sometimes makes
> sense at subsystem-level to re-use device's runtime PM callbacks.
>
> The PM core will at device_suspend_late disable runtime PM, after that
> we can safely operate on these callbacks. At suspend_late the device
> will be put into low power state by invoking the device's
> runtime_suspend callback, unless the runtime status is already
> suspended. At resume_early the state is restored by invoking the
> device's runtime_resume callback. Soon after the PM core will re-enable
> runtime PM before returning from device_resume_early.
>
> The new pm_generic functions are named pm_generic_suspend_late_runtime
> and pm_generic_resume_early_runtime, they are supposed to be used in
> pairs.
What happens if the subsystem uses the new functions as its late suspend/
early resume callbacks, but some of its drivers implement .suspend_late()
and .resume_early()?
Also, these are system suspend/resume callbacks, so the "runtime" part of
the names is kind of confusing. I have no idea for better naming at this
point, but still.
> Do note that these new generic callbacks will work smothly even with
> and without CONFIG_PM_RUNTIME, as long as the runtime PM callbacks are
> implemented inside CONFIG_PM instead of CONFIG_PM_RUNTIME.
>
> A special thanks to Alan Stern who came up with this idea.
>
> Cc: Kevin Hilman <khilman@xxxxxxxxxx>
> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> ---
> drivers/base/power/generic_ops.c | 86 ++++++++++++++++++++++++++++++++++++++
> include/linux/pm.h | 2 +
> 2 files changed, 88 insertions(+)
>
> diff --git a/drivers/base/power/generic_ops.c b/drivers/base/power/generic_ops.c
> index 5ee030a..3132768 100644
> --- a/drivers/base/power/generic_ops.c
> +++ b/drivers/base/power/generic_ops.c
> @@ -93,6 +93,49 @@ int pm_generic_suspend_late(struct device *dev)
> EXPORT_SYMBOL_GPL(pm_generic_suspend_late);
>
> /**
> + * pm_generic_suspend_late_runtime - Generic suspend_late callback for
> + * subsystems that wants to use runtime_suspend callbacks at suspend_late.
This has to be one line. You can add more description below the @dev line.
> + * @dev: Device to suspend.
> + */
> +int pm_generic_suspend_late_runtime(struct device *dev)
> +{
> + int (*callback)(struct device *);
> + int ret = 0;
> +
> + /*
> + * PM core has disabled runtime PM in device_suspend_late, thus we can
> + * safely check the device's runtime status and decide whether
> + * additional actions are needed to put the device into low power state.
> + * If so, we invoke the device's runtime_suspend callback.
> + * For the !CONFIG_PM_RUNTIME case, pm_runtime_status_suspended() always
> + * returns false and therefore the runtime_suspend callback will be
> + * invoked.
> + */
> + if (pm_runtime_status_suspended(dev))
> + return 0;
> +
> + if (dev->pm_domain)
> + callback = dev->pm_domain->ops.runtime_suspend;
> + else if (dev->type && dev->type->pm)
> + callback = dev->type->pm->runtime_suspend;
> + else if (dev->class && dev->class->pm)
> + callback = dev->class->pm->runtime_suspend;
> + else if (dev->bus && dev->bus->pm)
> + callback = dev->bus->pm->runtime_suspend;
> + else
> + callback = NULL;
> +
> + if (!callback && dev->driver && dev->driver->pm)
> + callback = dev->driver->pm->runtime_suspend;
> +
> + if (callback)
> + ret = callback(dev);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(pm_generic_suspend_late_runtime);
> +
> +/**
> * pm_generic_suspend - Generic suspend callback for subsystems.
> * @dev: Device to suspend.
> */
> @@ -237,6 +280,49 @@ int pm_generic_resume_early(struct device *dev)
> EXPORT_SYMBOL_GPL(pm_generic_resume_early);
>
> /**
> + * pm_generic_resume_early_runtime - Generic resume_early callback for
> + * subsystems that wants to use runtime_resume callbacks at resume_early.
Same here.
> + * @dev: Device to resume.
> + */
> +int pm_generic_resume_early_runtime(struct device *dev)
> +{
> + int (*callback)(struct device *);
> + int ret = 0;
> +
> + /*
> + * PM core has not yet enabled runtime PM in device_resume_early,
> + * thus we can safely check the device's runtime status and restore the
> + * previous state we had in device_suspend_late. If restore is needed
> + * we invoke the device's runtime_resume callback.
> + * For the !CONFIG_PM_RUNTIME case, pm_runtime_status_suspended() always
> + * returns false and therefore the runtime_resume callback will be
> + * invoked.
> + */
> + if (pm_runtime_status_suspended(dev))
> + return 0;
> +
> + if (dev->pm_domain)
> + callback = dev->pm_domain->ops.runtime_resume;
> + else if (dev->type && dev->type->pm)
> + callback = dev->type->pm->runtime_resume;
> + else if (dev->class && dev->class->pm)
> + callback = dev->class->pm->runtime_resume;
> + else if (dev->bus && dev->bus->pm)
> + callback = dev->bus->pm->runtime_resume;
> + else
> + callback = NULL;
> +
> + if (!callback && dev->driver && dev->driver->pm)
> + callback = dev->driver->pm->runtime_resume;
> +
> + if (callback)
> + ret = callback(dev);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(pm_generic_resume_early_runtime);
> +
> +/**
> * pm_generic_resume - Generic resume callback for subsystems.
> * @dev: Device to resume.
> */
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index a224c7f..5bce0d4 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -656,9 +656,11 @@ extern void dpm_for_each_dev(void *data, void (*fn)(struct device *, void *));
>
> extern int pm_generic_prepare(struct device *dev);
> extern int pm_generic_suspend_late(struct device *dev);
> +extern int pm_generic_suspend_late_runtime(struct device *dev);
> extern int pm_generic_suspend_noirq(struct device *dev);
> extern int pm_generic_suspend(struct device *dev);
> extern int pm_generic_resume_early(struct device *dev);
> +extern int pm_generic_resume_early_runtime(struct device *dev);
> extern int pm_generic_resume_noirq(struct device *dev);
> extern int pm_generic_resume(struct device *dev);
> extern int pm_generic_freeze_noirq(struct device *dev);
Thanks!
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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