linux-kernel - Re: [PATCH v4 1/2] ARM: keystone: pm: switch to use generic pm domains

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Date:	Thu, 20 Nov 2014 22:54:07 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Kevin Hilman <khilman@...nel.org>
Cc:	Grygorii Strashko <grygorii.strashko@...com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Arnd Bergmann <arnd@...db.de>, ssantosh@...nel.org,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Rob Herring <robh+dt@...nel.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: Re: [PATCH v4 1/2] ARM: keystone: pm: switch to use generic pm domains

On Thu, Nov 20, 2014 at 10:48 PM, Kevin Hilman <khilman@...nel.org> wrote:
>>> So what exactly are we talking about with "PM" clocks, and why are they
>>> "special" when it comes to PM domains?  IOW, why are the clocks to be
>>> managed during PM domain transitions for a given device any different
>>> than the clocks that need to be managed for a runtime suspend/resume (or
>>> system suspend/resume) sequence for the same device?
>>
>> (Speaking for my case, shmobile)
>>
>> They're not. The clocks to be managed during PM domain transitions are the
>> same as the clocks that need to be managed for a runtime suspend/resume
>> (or system suspend/resume) sequence.
>>
>> The special thing is that this is more a platform than a driver thing: the same
>> module may have a "PM/functional" clock (that is documented to enable/disable
>> the module) on one Soc, but noet on another.
>
> So why isn't the presence or absence of the clock described in the .dtsi
> for the SoC instead of being handled by special PM domain logic?

It is. Cfr. the presence/absence of clocks for renesas,rcar-gpio nodes.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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
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