[PATCH v2 2/4] ARM: exynos: Ensure PM domains are powered at initialization

Rafael J. Wysocki rjw at rjwysocki.net
Wed Oct 1 12:50:08 PDT 2014

On Wednesday, October 01, 2014 06:18:58 PM Sylwester Nawrocki wrote:
> On 01/10/14 16:41, Ulf Hansson wrote:
> > At ->probe() it's common practice for drivers/subsystems to bring their
> > devices to full power and without depending on CONFIG_PM_RUNTIME.
> > 
> > We could also expect that drivers/subsystems requires their device's
> > corresponding PM domains to be powered, to successfully complete a
> > ->probe() sequence.
> > 
> > Align to the behavior above, by ensuring all PM domains are powered
> > prior initialization of a generic PM domain.
> > 
> > Do note, since the generic PM domain will try to power off unused PM
> > domains at late_init, there should be no increased power consumption
> > over time, but potentially during boot.
> Wouldn't it be a better idea to power on the power domains which are
> turned off only when CONFIG_PM_RUNTIME is not enabled ? I had a plan
> to submit a patch doing that but unfortunately this has fallen through
> the cracks. At the moment mach-exynos/pm_domains.c is not even built in
> when CONFIG_PM_RUNTIME is disabled.
> I don't like the behaviour introduced in this patch to be the default,
> i.e. turning all possible power domains during boot sequence, even if
> some are not used and not needed. While we're trying to decrease the
> power consumption in any possible way this doesn't help at all.

Agreed (as stated before).

And I'm wondering why that comment of mine was ignored?

I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

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