linux-kernel - Re: [PATCH v8 4/9] regulator: Add support for MediaTek MT6363 SPMI PMIC Regulators

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Message-ID: <5635636.31r3eYUQgx@workhorse>
Date: Thu, 09 Oct 2025 16:41:56 +0200
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: linux-mediatek@...ts.infradead.org
Cc: lee@...nel.org, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
 matthias.bgg@...il.com, angelogioacchino.delregno@...labora.com,
 lgirdwood@...il.com, broonie@...nel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 kernel@...labora.com, wenst@...omium.org,
 igor.belwon@...tallysanemainliners.org,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Subject:
 Re: [PATCH v8 4/9] regulator: Add support for MediaTek MT6363 SPMI PMIC
 Regulators

On Friday, 3 October 2025 11:11:53 Central European Summer Time AngeloGioacchino Del Regno wrote:
> Add a driver for the regulators found on the MT6363 PMIC, fully
> controlled by SPMI interface.
> This PMIC regulates voltage with an input range of 2.6-5.0V, and
> features 10 buck converters and 26 LDOs.
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
>  drivers/regulator/Kconfig                  |  10 +
>  drivers/regulator/Makefile                 |   1 +
>  drivers/regulator/mt6363-regulator.c       | 935 +++++++++++++++++++++
>  include/linux/regulator/mt6363-regulator.h | 330 ++++++++
>  4 files changed, 1276 insertions(+)
>  create mode 100644 drivers/regulator/mt6363-regulator.c
>  create mode 100644 include/linux/regulator/mt6363-regulator.h
> 
> [...]
> diff --git a/drivers/regulator/mt6363-regulator.c b/drivers/regulator/mt6363-regulator.c
> new file mode 100644
> index 000000000000..812775072eb5
> --- /dev/null
> +++ b/drivers/regulator/mt6363-regulator.c
> [...]
> +
> +static int mt6363_regulator_set_mode(struct regulator_dev *rdev,
> +				     unsigned int mode)
> +{
> +	struct mt6363_regulator_info *info = rdev_get_drvdata(rdev);
> +	struct regmap *regmap = rdev->regmap;
> +	int cur_mode, ret;
> +
> +	if (!info->modeset_reg && mode == REGULATOR_MODE_FAST)
> +		return -EOPNOTSUPP;
> +
> +	switch (mode) {
> +	case REGULATOR_MODE_FAST:
> +		ret = mt6363_buck_unlock(regmap, true);
> +		if (ret)
> +			break;
> +
> +		ret = regmap_set_bits(regmap, info->modeset_reg, info->modeset_mask);
> +
> +		mt6363_buck_unlock(regmap, false);
> +		break;
> +	case REGULATOR_MODE_NORMAL:
> +		cur_mode = mt6363_regulator_get_mode(rdev);
> +		if (cur_mode < 0) {
> +			ret = cur_mode;
> +			break;
> +		}
> +
> +		if (cur_mode == REGULATOR_MODE_FAST) {
> +			ret = mt6363_buck_unlock(regmap, true);
> +			if (ret)
> +				break;
> +
> +			ret = regmap_clear_bits(regmap, info->modeset_reg, info->modeset_mask);
> +
> +			mt6363_buck_unlock(regmap, false);
> +			break;
> +		} else if (cur_mode == REGULATOR_MODE_IDLE) {
> +			ret = regmap_clear_bits(regmap, info->lp_mode_reg, info->lp_mode_mask);
> +			if (ret == 0)
> +				usleep_range(100, 200);
> +		} else {
> +			ret = 0;

Just initialise ret to 0 at the start of the function scope when
you declare it. You've already missed an uninitialised use once,
and playing these branch games is just asking for more trouble
in the future. There's no micro-optimisation you're doing here,
clang produces the same assembly for both zero initialised and
the else branch version you're doing here.

> +		}
> +		break;
> +	case REGULATOR_MODE_IDLE:
> +		ret = regmap_set_bits(regmap, info->lp_mode_reg, info->lp_mode_mask);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	if (ret) {
> +		dev_err(&rdev->dev, "Failed to set mode %u: %d\n", mode, ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> [...]

Kind regards,
Nicolas Frattaroli