Re: [PATCH/RFC 3/4] of/clk: Register clocks suitable for Runtime PM with the PM core

Laurent Pinchart
2014-04-30T21:23:11Z

Hi Ulf and Geert,

On Thursday 24 April 2014 15:11:24 Ulf Hansson wrote:
> On 24 April 2014 12:13, Geert Uytterhoeven <geert+renesas@glider.be> wrote:
> > When adding a device from DT, check if its clocks are suitable for Runtime
> > PM, and register them with the PM core.
> > If Runtime PM is disabled, just enable the clock.
> >
> > This allows the PM core to automatically manage gate clocks of devices for
> > Runtime PM.
>
> Normally I don't think it's a good idea to "automatically" manage
> clocks from PM core or any other place but from the driver (and
> possibly the subsystem).
>
> The reason is simply that we hide things that normally is supposed to
> be handled by the driver. Typically a cross SOC driver should work
> fine both with and without a pm_domain. It should also not rely on
> CONFIG_PM_RUNTIME.

That's a very good point. Geert, what do you think should happen if
CONFIG_PM_RUNTIME is not set ? I don't have a strong opinion (yet) on whether
we could require CONFIG_PM_RUNTIME, but it would indeed be nice to support
both cases. One option would be to keep the clocks enabled unconditionally in
that case, as not setting CONFIG_PM_RUNTIME means that the user doesn't care
(or cares less) about power consumption.

> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

--
Regards,

Laurent Pinchart