linux-kernel - Re: [PATCH v2 2/3] ARM: keystone: pm: switch to use generic pm domains

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Date:	Wed, 22 Oct 2014 17:09:36 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Ulf Hansson <ulf.hansson@...aro.org>
Cc:	Grygorii Strashko <grygorii.strashko@...com>,
	Santosh Shilimkar <santosh.shilimkar@...il.com>,
	ssantosh@...nel.org, "Rafael J. Wysocki" <rjw@...ysocki.net>,
	Kevin Hilman <khilman@...aro.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	"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>
Subject: Re: [PATCH v2 2/3] ARM: keystone: pm: switch to use generic pm domains

Hi Ulf,

On Wed, Oct 22, 2014 at 5:01 PM, Ulf Hansson <ulf.hansson@...aro.org> wrote:
>>>> +void keystone_pm_domain_attach_dev(struct device *dev)
>>>>   {
>>>> +    struct clk *clk;
>>>>       int ret;
>>>> +    int i = 0;
>>>>
>>>>       dev_dbg(dev, "%s\n", __func__);
>>>>
>>>> -    ret = pm_generic_runtime_suspend(dev);
>>>> -    if (ret)
>>>> -        return ret;
>>>> -
>>>> -    ret = pm_clk_suspend(dev);
>>>> +    ret = pm_clk_create(dev);
>>>>       if (ret) {
>>>> -        pm_generic_runtime_resume(dev);
>>>> -        return ret;
>>>> +        dev_err(dev, "pm_clk_create failed %d\n", ret);
>>>> +        return;
>>>> +    };
>>>> +
>>>> +    while ((clk = of_clk_get(dev->of_node, i++)) && !IS_ERR(clk)) {
>>>> +        ret = pm_clk_add_clk(dev, clk);
>>>> +        if (ret) {
>>>> +            dev_err(dev, "pm_clk_add_clk failed %d\n", ret);
>>>> +            goto clk_err;
>>>> +        };
>>>>       }
>>>>
>>>> -    return 0;
>>>> +    if (!IS_ENABLED(CONFIG_PM_RUNTIME)) {
>>> Can we not okkup two seperate callbacks instead of above check ?
>>> I don't like this CONFIG check here. Its slightly better version of
>>> ifdef in middle of the code.
>>
>> I've found more-less similar comment on patch
>> "Re: [PATCH v3 1/3] power-domain: add power domain drivers for Rockchip platform"
>> https://lkml.org/lkml/2014/10/17/257
>>
>> So, Would you like me to create patch which will enable clocks in pm_clk_add/_clk()
>> in case !IS_ENABLED(CONFIG_PM_RUNTIME)
>
> I am wondering whether we actually should/could do this, no matter of
> CONFIG_PM_RUNTIME.
>
> Typically, for configurations that uses CONFIG_PM_RUNTIME, the PM
> clocks through pm_clk_suspend(), will be gated once the device becomes
> runtime PM suspended. Right?

Doing it unconditionally means we'll have lots of unneeded clocks running
for a short while.

Are you trying to repeat power-up-all-PM-domains-during-boot for
clocks, too? ;-)

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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