linux-kernel - Re: [PATCH 1/2] regulator: anatop: Add power gating support to digital LDOs

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Message-ID: <20140210131557.GB1757@sirena.org.uk>
Date:	Mon, 10 Feb 2014 13:15:57 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Philipp Zabel <p.zabel@...gutronix.de>
Cc:	linux-kernel@...r.kernel.org, Liam Girdwood <lgirdwood@...il.com>,
	Shawn Guo <shawn.guo@...aro.org>,
	Anson Huang <b20788@...escale.com>, kernel@...gutronix.de
Subject: Re: [PATCH 1/2] regulator: anatop: Add power gating support to
 digital LDOs

On Thu, Feb 06, 2014 at 03:43:32PM +0100, Philipp Zabel wrote:
> The ARM, PU, and SOC LDOs in the i.MX6 PMU can completely gate
> their power output. Since power gating is configured by writing
> zero to the voltage target bitfield,, store a copy of the
> voltage selector to be restored when reenabling the regulator.

This is mostly good but...

>  static int anatop_regmap_set_voltage_sel(struct regulator_dev *reg,
>  					unsigned selector)
>  {
>  	struct anatop_regulator *anatop_reg = rdev_get_drvdata(reg);
> +	int ret;
>  
>  	if (!anatop_reg->control_reg)
>  		return -ENOTSUPP;
>  
> -	return regulator_set_voltage_sel_regmap(reg, selector);
> +	ret = regulator_set_voltage_sel_regmap(reg, selector);
> +	if (!ret)
> +		anatop_reg->sel = selector;
> +	return ret;
>  }

...I don't understand this.  If the regulator is disabled won't this
cause it to be reenabled since we just write the stored selector in to
do that?  What I'd expect to see happening is the data being written to
the cache always and only written to the hardware if it's enabled.

> +static int anatop_regmap_disable(struct regulator_dev *reg)
> +{
> +	struct anatop_regulator *anatop_reg = rdev_get_drvdata(reg);
> +
> +	if (!anatop_is_core_reg(anatop_reg))
> +		return -ENOTSUPP;
> +
> +	return regulator_set_voltage_sel_regmap(reg, LDO_POWER_GATE);
> +}

It's starting to seem like it's worth having separate ops for the core
regulator rather than all these conditionals.

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