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

Geert Uytterhoeven
2014-04-30T22:06:07Z

Hi Laurent,

On Wed, Apr 30, 2014 at 11:23 PM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> 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.

This is already handled by my patch. If CONFIG_PM_RUNTIME is disabled,
the clocks are enabled by calling clk_prepare_enabled().

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds