linux-kernel - Re: [PATCH 6/7] regulator: add mt6357 regulator

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Message-ID: <YpYSQXWU1NlM4JU6@sirena.org.uk>
Date:   Tue, 31 May 2022 15:04:01 +0200
From:   Mark Brown <broonie@...nel.org>
To:     Fabien Parent <fparent@...libre.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 6/7] regulator: add mt6357 regulator

On Tue, May 31, 2022 at 02:49:58PM +0200, Fabien Parent wrote:

> @@ -0,0 +1,485 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2022 MediaTek Inc.
> + * Copyright (c) 2022 BayLibre, SAS.
> + * Author: Chen Zhong <chen.zhong@...iatek.com>
> + * Author: Fabien Parent <fparent@...libre.com>
> + *
> + * Based on mt6397-regulator.c
> + */

Please make the entire comment a C++ one so things look more
intentional.

> +static int mt6357_set_voltage_sel(struct regulator_dev *rdev,
> +				  unsigned int selector)
> +{
> +	int idx, ret;
> +	const u32 *pvol;
> +	struct mt6357_regulator_info *info = rdev_get_drvdata(rdev);
> +
> +	pvol = info->index_table;
> +
> +	idx = pvol[selector];
> +	ret = regmap_update_bits(rdev->regmap, info->desc.vsel_reg,
> +				 info->desc.vsel_mask,
> +				 idx << 8);
> +
> +	return ret;
> +}

I don't really understand what's going on with selectors here -
the general idea with selectors is that we just pass the value
that's written to the bitfield around and have mapping functions
which convert to/from voltages.  Here we're mapping the selectors
using this index_table thing which seems like an extra layer of
mapping.  What's the story there?  

I don't see why this can't just use the functions in helpers.c.
It looks like you can use _list_voltage_table() -EINVALs in there
for invalid selectors and _map_voltage_iterate().  Note that
n_voltages is effectively a maximum selector.

> +static int mt6357_get_buck_voltage_sel(struct regulator_dev *rdev)
> +{
> +	int ret, regval;
> +	struct mt6357_regulator_info *info = rdev_get_drvdata(rdev);
> +
> +	ret = regmap_read(rdev->regmap, info->da_vsel_reg, &regval);
> +	if (ret != 0) {
> +		dev_err(&rdev->dev,
> +			"Failed to get mt6357 Buck %s vsel reg: %d\n",
> +			info->desc.name, ret);
> +		return ret;
> +	}
> +
> +	ret = (regval & info->da_vsel_mask) >> info->da_vsel_shift;
> +
> +	return ret;
> +}

This looks like it should just be able to use
regulator_get_voltage_sel_regmap()?

Otherwise this looks good.

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