Subject: [PATCH] PM / Domains: Power on the PM domain right after attach completes

From: [email-masked] (Kevin Hilman)
Date: Mon, 17 Nov 2014 10:28:56 -0800

Ulf Hansson <[email-masked]> writes:

> The amba bus, amba drivers and a vast amount of platform drivers which
> enables runtime PM, don't invoke a pm_runtime_get_sync() while probing
> their devices.
>
> Instead, once they have turned on their PM resourses during ->probe()
> and are ready to handle I/O, these invokes pm_runtime_set_active() to
> synchronize its state towards the runtime PM core.
>
> From a runtime PM point of view this behavior is perfectly acceptable,

In the context of PM domains that can be dynamically powered on/off, I'm
not so sure it's perfectly acceptable anymore.

Why doesn't the bus do a _get_sync() instead of a _get_noresume()
followed by a _set_active().  

By using the _get_noresume() you're bypassing the paths that would bring
up your PM domain.

Kevin