On Monday, February 14, 2011, Alan Stern wrote:
> On Sat, 12 Feb 2011, Rafael J. Wysocki wrote:
>
> > From: Rafael J. Wysocki <rjw@xxxxxxx>
> >
> > The platform bus type is often used to handle Systems-on-a-Chip (SoC)
> > where all devices are represented by objects of type struct
> > platform_device. In those cases the same "platform" device driver
> > may be used with multiple different system configurations, but the
> > actions needed to put the devices it handles into a low-power state
> > and back into the full-power state may depend on the design of the
> > given SoC. The driver, however, cannot possibly include all the
> > information necessary for the power management of its device on all
> > the systems it is used with. Moreover, the device hierarchy in its
> > current form also is not suitable for representing this kind of
> > information.
> >
> > The patch below attempts to address this problem by introducing
> > objects of type struct dev_power_domain that can be used for
> > representing power domains within a SoC. Every struct
> > dev_power_domain object provides a sets of device power
> > management callbacks that can be used to perform what's needed for
> > device power management in addition to the operations carried out by
> > the device's driver and subsystem.
> >
> > Namely, if a struct dev_power_domain object is pointed to by the
> > pwr_domain field in a struct device, the callbacks provided by its
> > ops member will be executed in addition to the corresponding
> > callbacks provided by the device's subsystem and driver during all
> > power transitions.
>
> Overall this looks very good.
>
> > Index: linux-2.6/include/linux/pm.h
> > ===================================================================
> > --- linux-2.6.orig/include/linux/pm.h
> > +++ linux-2.6/include/linux/pm.h
> > @@ -463,6 +463,14 @@ struct dev_pm_info {
> >
> > extern void update_pm_runtime_accounting(struct device *dev);
> >
> > +/*
> > + * Power domains provide callbacks that are executed during system suspend,
> > + * hibernation, system resume and during runtime PM transitions along with
> > + * subsystem-level and driver-level callbacks.
> > + */
> > +struct dev_power_domain {
> > + struct dev_pm_ops ops;
> > +};
>
> I don't have a clear picture of how people are going to want to use
> these dev_power_domain structures. Should there be a
>
> void *priv;
>
> member as well?
Well, I'm not sure. What would be the purpose of it?
Rafael
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