linux-kernel - Re: [PATCH 4/6] regulator: hi6421v530: add driver for hi6421v530 voltage regulator

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Date:   Fri, 26 May 2017 12:38:22 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Guodong Xu <guodong.xu@...aro.org>
Cc:     lee.jones@...aro.org, robh+dt@...nel.org, mark.rutland@....com,
        xuwei5@...ilicon.com, catalin.marinas@....com, will.deacon@....com,
        lgirdwood@...il.com, khilman@...libre.com, arnd@...db.de,
        gregory.clement@...e-electrons.com, olof@...om.net,
        thomas.petazzoni@...e-electrons.com, yamada.masahiro@...ionext.com,
        riku.voipio@...aro.org, treding@...dia.com, krzk@...nel.org,
        eric@...olt.net, damm+renesas@...nsource.se,
        ard.biesheuvel@...aro.org, linus.walleij@...aro.org,
        geert+renesas@...der.be, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        hw.wangxiaoyin@...ilicon.com
Subject: Re: [PATCH 4/6] regulator: hi6421v530: add driver for hi6421v530
 voltage regulator

On Fri, May 26, 2017 at 02:35:16PM +0800, Guodong Xu wrote:

Overall this driver needs quite a lot of modernization, it's at least a
couple of years out of date in how it's using the framework - there's
barely any use of helpers.  It does look like it should be fairly easy
to get it up to date though, it's mostly going to be a case of deleting
code that's reimplementing helpers rather than anything else.

> +/*
> + * struct hi6421c530_regulator_pdata - Hi6421V530 regulator data
> + * of platform device.
> + * @lock: mutex to serialize regulator enable
> + */
> +struct hi6421v530_regulator_pdata {
> +	struct mutex lock;
> +};

This isn't platform data so it probably shouldn't be called pdata.  I
also can't tell what the lock is protecting, every use seems to be a
call to regmap_update_bits() which is atomic anyway - could we just drop
the whole thing?

> +static int hi6421v530_regulator_enable(struct regulator_dev *rdev)
> +{
> +	struct hi6421v530_regulator_pdata *pdata;
> +	int ret = 0;
> +
> +	pdata = dev_get_drvdata(rdev->dev.parent);
> +	mutex_lock(&pdata->lock);
> +
> +	ret = regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
> +			rdev->desc->enable_mask,
> +			1 << (ffs(rdev->desc->enable_mask) - 1));
> +
> +	mutex_unlock(&pdata->lock);
> +	return ret;
> +}

This looks like it should be able to use the regmap helpers for all the
enable operations rather than open coding.  

> +static int hi6421v530_regulator_set_voltage(struct regulator_dev *rdev,
> +						unsigned int sel)
> +{
> +	struct hi6421v530_regulator_pdata *pdata;
> +	int ret = 0;
> +
> +	pdata = dev_get_drvdata(rdev->dev.parent);
> +	mutex_lock(&pdata->lock);
> +
> +	ret = regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
> +				rdev->desc->vsel_mask,
> +				sel << (ffs(rdev->desc->vsel_mask) - 1));

Same for all the voltage operations :(

> +	rdev->constraints->valid_modes_mask = info->mode_mask;
> +	rdev->constraints->valid_ops_mask |=
> +			REGULATOR_CHANGE_VOLTAGE | REGULATOR_CHANGE_MODE;

The driver should *never* modify constraints, it's up to the machine
integration to say what can be supported on a given board.

> +	np = of_get_child_by_name(dev->parent->of_node, "regulators");
> +	if (!np)
> +		return -ENODEV;
> +
> +	ret = of_regulator_match(dev, np,
> +				 hi6421v530_regulator_match,
> +				 ARRAY_SIZE(hi6421v530_regulator_match));

Don't open code this, use of_match and regulators_node.

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