linux-kernel - Re: [RFC PATCH 0/3] PM / clock_ops: allow to specify custom pm_clk

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Date:	Wed, 17 Sep 2014 17:03:03 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Grygorii Strashko <grygorii.strashko@...com>
Cc:	Kevin Hilman <khilman@...aro.org>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Ben Dooks <ben.dooks@...ethink.co.uk>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux-sh list <linux-sh@...r.kernel.org>
Subject: Re: [RFC PATCH 0/3] PM / clock_ops: allow to specify custom
 pm_clk_notifier callback

Hi Grygorii,

On Tue, Sep 9, 2014 at 3:41 PM, Grygorii Strashko
<grygorii.strashko@...com> wrote:
>> Since you're essentially gutting clock_ops, have you considered
>> migrating to genpd and having your own pm_domain ops that manage your clocks?
>
> Yes. I've thought about using genpd. But:
> - PM domain is not merged in 3.17 and I don't know if it will be merged in 3.18 :(
> http://www.spinics.net/lists/arm-kernel/msg357003.html

Let's wait and see...

> - To switch using PM domains I will need to create PM domain node PER EACH device,
> (if I understand PM domain bindings right). For example:
>
> +power_netcp: power-controller@0 {
> +               compatible = "keystone,power-controller";
> +               #power-domain-cells = <0>;
> +               clocks = <&clkcpgmac>, <&clkpa>, <&chipclk12>;
> +       };
>
> netcp: netcp@...0000 {
>                 reg = <0x2620110 0x8>;
> +               power-domains = <&power_netcp>;
> ...
> }

I think you can have one power-controller, and add the clocks and
power-domains properties to the individual device nodes.

Then the power-controller driver can use the attach callback
introduced in "[PATCH/RFC v2 04/12] PM / Domains: Add genpd attach/detach
callbacks" (https://lkml.org/lkml/2014/9/16/429) to set up the clocks?

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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