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

From: Ulf Hansson
Date: Wed Oct 22 2014 - 11:29:02 EST


On 22 October 2014 17:09, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> Hi Ulf,
>
> On Wed, Oct 22, 2014 at 5:01 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> 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? ;-)

This is related, but there are a difference. :-)

As long as the pm_clk_add() is being invoked from the ->attach_dev()
callback, we are in the probe path. Certainly we would like to have
clocks enabled while probing, don't you think?

If we wouldn't enable the clocks for CONFIG_PM_RUNTIME, when will
those be enabled?

Kind regards
Uffe
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