linux-kernel - Re: [PATCH 2/2] regulator: Add support for MAX77686.

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Message-ID: <20120509184709.GC32037@sirena.org.uk>
Date:	Wed, 9 May 2012 19:47:09 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Yadwinder Singh <yadi.brar@...sung.com>
Cc:	linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/2] regulator: Add support for MAX77686.

On Wed, May 09, 2012 at 09:54:55PM +0530, Yadwinder Singh wrote:

> +/* Voltage maps in mV */
> +static const struct voltage_map_desc ldo_voltage_map_desc = {
> +	.min = 800,	.max = 3950,	.step = 50,	.n_bits = 6,
> +};				/* LDO3 ~ 5, 9 ~ 14, 16 ~ 26 */

Hrm, funnily enough I was just thinking about factoring this stuff out
into the core after a conversation with Graeme Gregory the other week.
Let's do that...

> +	[MAX77686_EN32KHZ_AP] = NULL,
> +	[MAX77686_EN32KHZ_CP] = NULL,

Now that the generic clock API is in mainline these should be moved over
to use it.

> +static int max77686_get_voltage_unit(int rid)
> +{
> +	int unit = 0;
> +
> +	switch (rid) {
> +	case MAX77686_BUCK2...MAX77686_BUCK4:
> +		unit = 1;	/* BUCK2,3,4 is uV */
> +		break;
> +	default:
> +		unit = 1000;

Why not just list everything in uV?

> +static int max77686_get_voltage(struct regulator_dev *rdev)
> +{

Implement get_voltage_sel().

> +static inline int max77686_get_voltage_proper_val(const struct voltage_map_desc
> +						  *desc, int min_vol,
> +						  int max_vol)
> +{
> +	int i = 0;
> +
> +	if (desc == NULL)
> +		return -EINVAL;
> +
> +	if (max_vol < desc->min || min_vol > desc->max)
> +		return -EINVAL;
> +
> +	while (desc->min + desc->step * i < min_vol &&
> +	       desc->min + desc->step * i < desc->max)
> +		i++;

Why are you iterating here?  Calculate!  Though like I say let's factor
this out anyway.

> +	if (rid == MAX77686_BUCK2 || rid == MAX77686_BUCK3 ||
> +	    rid == MAX77686_BUCK4) {
> +		/* If the voltage is increasing */
> +		if (org < i)
> +			udelay(DIV_ROUND_UP(desc->step * (i - org),
> +					    ramp[max77686->ramp_delay]));
> +	}

Don't do this, implement set_voltage_time_sel().

> +	.enable = max77686_reg_enable,
> +	.disable = max77686_reg_disable,
> +	.set_suspend_enable = max77686_reg_enable,
> +	.set_suspend_disable = max77686_reg_disable,

You've got the same ops for suspend and non-suspend cases here, this is
clearly buggy.

> +/* count the number of regulators to be supported in pmic */
> +	pdata->num_regulators = 0;

Coding style.

> +	if (iodev->dev->of_node) {
> +		ret = max77686_pmic_dt_parse_pdata(iodev, pdata);
> +		if (ret)
> +			return ret;

This ought to use of_regulator_match().

> +	}
> +
> +	if (!pdata) {
> +		dev_err(&pdev->dev, "platform data not found\n");
> +		return -ENODEV;
> +	}

This should be totally fine.

> +	max77686 = kzalloc(sizeof(struct max77686_data), GFP_KERNEL);
> +	if (!max77686)
> +		return -ENOMEM;

devm_kzalloc().

> +	if (pdata->ramp_delay) {
> +		max77686->ramp_delay = pdata->ramp_delay;
> +		max77686_update_reg(i2c, MAX77686_REG_BUCK2CTRL1,
> +			RAMP_VALUE, RAMP_MASK);

This appears not to actually use the value passed in as platform_data.

> +
> +	for (i = 0; i < pdata->num_regulators; i++) {
> +		const struct voltage_map_desc *desc;
> +		int id = pdata->regulators[i].id;
> +
> +		desc = reg_voltage_map[id];
> +		if (desc)
> +			regulators[id].n_voltages =
> +			    (desc->max - desc->min) / desc->step + 1;
> +
> +		rdev[i] = regulator_register(&regulators[id], max77686->dev,
> +					     pdata->regulators[i].initdata,
> +					     max77686, NULL);

No, you should unconditionally register all regulators the device
physically has.  This is useful for debug and simplifies the code.
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