linux-kernel - Re: [PATCH] regulator: mt6360: Add support for MT6360 regulator

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Date:   Thu, 18 Jun 2020 19:35:24 +0800
From:   Gene Chen <gene.chen.richtek@...il.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     matthias.bgg@...il.com, lgirdwood@...il.com,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Gene Chen <gene_chen@...htek.com>, Wilma.Wu@...iatek.com,
        shufan_lee@...htek.com, cy_huang@...htek.com,
        benjamin.chao@...iatek.com
Subject: Re: [PATCH] regulator: mt6360: Add support for MT6360 regulator

Mark Brown <broonie@...nel.org> 於 2020年6月4日 週四 下午9:39寫道：
>
> On Thu, Jun 04, 2020 at 03:06:27PM +0800, Gene Chen wrote:
>
> This looks nice and simple, a few fairly small comments below but high
> level it's basically fine.
>
> > --- /dev/null
> > +++ b/drivers/regulator/mt6360-regulator.c
> > @@ -0,0 +1,571 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2020 MediaTek Inc.
>
> Please make the entire comment a C++ one so things look more
> intentional.
>

ACK

> > +     for (i = 0; i < devdata->num_irq_descs; i++) {
> > +             irq_desc = devdata->irq_descs + i;
> > +             if (unlikely(!irq_desc->name))
> > +                     continue;
>
> Do we really need an unlikely here?  This shouldn't be a hot path.
>
> > +static int mt6360_regulator_set_mode(
> > +                               struct regulator_dev *rdev, unsigned int mode)
> > +{
>
> > +     switch (1 << (ffs(mode) - 1)) {
> > +     case REGULATOR_MODE_NORMAL:
>
> I don't understand why this isn't just a straight switch on mode?
>

ACK, we will fix it

> > +static unsigned int mt6360_regulator_get_mode(struct regulator_dev *rdev)
> > +{
> > +     const struct mt6360_regulator_desc *desc =
> > +                            (const struct mt6360_regulator_desc *)rdev->desc;
> > +     int shift = ffs(desc->mode_get_mask) - 1, ret;
> > +     unsigned int val = 0;
> > +
> > +     default:
> > +             ret = 0;
> > +     }
>
> If we can't parse a valid value from the hardware then that's an error.
>

ACK

> > +static int mt6360_regulator_reg_write(void *context,
> > +                                   unsigned int reg, unsigned int val)
> > +{
> > +     struct mt6360_regulator_data *mrd = context;
> > +     u8 chunk[4] = {0};
> > +
> > +     /* chunk 0 ->i2c addr, 1 -> reg_addr, 2 -> reg_val 3-> crc8 */
> > +     chunk[0] = (mrd->i2c->addr & 0x7f) << 1;
> > +     chunk[1] = reg & 0x3f;
> > +     chunk[2] = (u8)val;
> > +     chunk[3] = crc8(mrd->crc8_table, chunk, 3, 0);
> > +     /* also dummy one byte */
> > +     return i2c_smbus_write_i2c_block_data(mrd->i2c, chunk[1], 3, chunk + 2);
> > +}
>
> Oh, wow - that's a fun I/O interface!
>

MT6360 PMIC/LDO part use CRC to avoid i2c write mistaken

> > +static const struct of_device_id __maybe_unused mt6360_regulator_of_id[] = {
> > +     {
> > +             .compatible = "mediatek,mt6360_pmic",
> > +             .data = (void *)&mt6360_pmic_devdata,
> > +     },
> > +     {
> > +             .compatible = "mediatek,mt6360_ldo",
> > +             .data = (void *)&mt6360_ldo_devdata,
> > +     },
> > +     {},
> > +};
> > +MODULE_DEVICE_TABLE(of, mt6360_regulator_of_id);
>
> I don't see any DT bindings documentation for this, documentation is
> required for all new bindings.
>

ACK, we will update binding document

> > +     mrd->regmap = devm_regmap_init(&(mrd->i2c->dev),
> > +                                    NULL, mrd, devdata->regmap_config);
> > +     if (IS_ERR(mrd->regmap)) {
> > +             dev_err(&pdev->dev, "Failed to register regmap\n");
> > +             return PTR_ERR(mrd->regmap);
> > +     }
>
> This looks like a MFD so it's surprising to see us defining a regmap at
> this level.  Why are we doing this?

because other sub-device (e.g. CHARGER/LED/ADC) no need CRC when i2c R/W
we will merge remgap into mfd, and use "bank" strategy to distinguish
different part