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?
Alan Stern
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