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

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Message-ID: <CAFGCpxyc6YnXQQk5TFzh5b7mByQuFg5h+nYfPYyJUdjvforYHA@mail.gmail.com>
Date:   Sat, 27 May 2017 17:47:25 +0800
From:   Guodong Xu <guodong.xu@...aro.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Lee Jones <lee.jones@...aro.org>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "xuwei (O)" <xuwei5@...ilicon.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Kevin Hilman <khilman@...libre.com>,
        Arnd Bergmann <arnd@...db.de>,
        Gregory CLEMENT <gregory.clement@...e-electrons.com>,
        Olof Johansson <olof@...om.net>,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Riku Voipio <riku.voipio@...aro.org>,
        Thierry Reding <treding@...dia.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Eric Anholt <eric@...olt.net>, damm+renesas@...nsource.se,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "hw Wang(Xiaoyin)" <hw.wangxiaoyin@...ilicon.com>
Subject: Re: [PATCH 4/6] regulator: hi6421v530: add driver for hi6421v530
 voltage regulator

On Fri, May 26, 2017 at 7:38 PM, Mark Brown <broonie@...nel.org> wrote:
> 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 couple of years out of date in how it's using the framework - there's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?

In original hi6421 chip, this lock can protect from enabling multiple
LDOs simultaneously. Because it cannot afford such surging current.

I will double check whether this is still the case for hi6421v530. If
not, I will remove 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.

I will fix that.

Thanks Mark for your review.

-Guodong