Re: [PATCH] PM: add dpm_use_runtime_{suspend, resume} helper functions

Rafael J. Wysocki
2010-03-03T21:33:14Z

On Wednesday 03 March 2010, Alan Stern wrote:
> On Tue, 2 Mar 2010, Rafael J. Wysocki wrote:
>
> > +/**
> > + * __pm_generic_call - Generic suspend/freeze/poweroff/thaw subsystem callback.
> > + * @dev: Device to handle.
> > + * @event: PM transition of the system under way.
> > + *
> > + * If the device has not been suspended at run time, execute the
> > + * suspend/freeze/poweroff/thaw callback provided by its driver, if defined, and
> > + * return the error code returned by it. Otherwise, return zero.
> > + */
> > +static int __pm_generic_call(struct device *dev, int event)
> > +{
> > + const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
> > + int (*callback)(struct device *);
> > +
> > + if (!pm || pm_runtime_suspended(dev))
> > + return 0;
> > +
> > + switch (event) {
> > + case PM_EVENT_SUSPEND:
> > + callback = pm->suspend;
> > + break;
> > + case PM_EVENT_FREEZE:
> > + callback = pm->freeze;
> > + break;
> > + case PM_EVENT_HIBERNATE:
> > + callback = pm->poweroff;
> > + break;
> > + case PM_EVENT_THAW:
> > + callback = pm->thaw;
> > + break;
> > + default:
> > + callback = NULL;
> > + break;
> > + }
> > +
> > + return callback ? callback(dev) : 0;
> > +}
>
> Are you sure you want to avoid calling pm->thaw if the device is
> runtime-suspended? Maybe it would be better to treat thaw like resume
> or restore.

In .freeze() we check if the device is runtime suspended and skip the driver's
.freeze() in that case, so the device is still suspended. I don't think
.thaw() should call the driver's .thaw() in that case and change the runtime
suspended status (that won't serve any practical purpose IMO).

> > --- linux-2.6.orig/include/linux/pm_runtime.h
> > +++ linux-2.6/include/linux/pm_runtime.h
> > @@ -62,6 +62,11 @@ static inline void device_set_run_wake(s
> > dev->power.run_wake = enable;
> > }
> >
> > +static inline bool pm_runtime_suspended(struct device *dev)
> > +{
> > + return dev->power.runtime_status == RPM_SUSPENDED;
> > +}
> > +
>
> You didn't add this to the documentation file.

Yes, I realized that after sending the patch, sorry.

Rafael