linux-kernel - Re: [PATCH v7 1/3] power-domain: add power domain drivers for Rockchip platform

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Message-ID: <20141024164431.GE19933@dtor-ws>
Date:	Fri, 24 Oct 2014 09:44:31 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	"jinkun.hong" <jinkun.hong@...k-chips.com>
Cc:	linus.walleij@...aro.org, linux-arm-kernel@...ts.infradead.org,
	Russell King <linux@....linux.org.uk>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Grant Likely <grant.likely@...aro.org>,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	Randy Dunlap <rdunlap@...radead.org>,
	linux-doc@...r.kernel.org, dianders@...omium.org,
	Heiko Stuebner <heiko@...ech.de>,
	linux-rockchip@...ts.infradead.org,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Jack Dai <jack.dai@...k-chips.com>
Subject: Re: [PATCH v7 1/3] power-domain: add power domain drivers for
 Rockchip platform

Hi Jinkun,

On Fri, Oct 24, 2014 at 12:29:19AM -0700, jinkun.hong wrote:
> +static int rockchip_pd_power(struct rockchip_domain *pd, bool power_on)
> +{
> +	int ret = 0;
> +	struct rockchip_dev_entry *de;
> +
> +	mutex_lock(&pd->dev_lock);
> +	/* no clk, set power domain will fail */
> +	if (list_empty(&pd->dev_list)) {
> +		pr_err("%s: no devices in %s power domain\n", __func__,
> +			pd->base.name);
> +		goto out;
> +	}
> +
> +	list_for_each_entry(de, &pd->dev_list, node) {
> +		pm_clk_resume(de->dev);
> +	}
> +
> +	ret = rockchip_pmu_set_power_domain(pd, power_on);
> +
> +	list_for_each_entry(de, &pd->dev_list, node) {
> +		pm_clk_suspend(de->dev);
> +	}
> +out:
> +	mutex_unlock(&pd->dev_lock);
> +	return ret;
> +}

For my education, could you please tell me why we need to enable all
clocks of all devices in a power domain when we are talking to the PMU
and then turn them immediately off? Would not we want to enable clocks
in start()) callbacks, like Ulf mentioned?

Thanks.

-- 
Dmitry
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