linux-kernel - Re: [PATCH v3 07/14] mfd: mt6370: Add Mediatek MT6370 support

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Message-ID: <Ys58hr3AK/p/4/ng@google.com>
Date:   Wed, 13 Jul 2022 09:04:22 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     ChiaEn Wu <peterwu.pub@...il.com>
Cc:     Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>, Pavel Machek <pavel@....cz>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Sebastian Reichel <sre@...nel.org>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        "Krogerus, Heikki" <heikki.krogerus@...ux.intel.com>,
        Helge Deller <deller@....de>,
        ChiaEn Wu <chiaen_wu@...htek.com>,
        Alice Chen <alice_chen@...htek.com>,
        ChiYuan Huang <cy_huang@...htek.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        USB <linux-usb@...r.kernel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        "open list:FRAMEBUFFER LAYER" <linux-fbdev@...r.kernel.org>,
        szuni chen <szunichen@...il.com>
Subject: Re: [PATCH v3 07/14] mfd: mt6370: Add Mediatek MT6370 support

On Wed, 13 Jul 2022, ChiaEn Wu wrote:

> Hi Lee,
> 
> Thanks for your reply.
> 
> Lee Jones <lee.jones@...aro.org> 於 2022年7月12日 週二 晚上11:29寫道：
> >
> > On Thu, 23 Jun 2022, ChiaEn Wu wrote:
> >
> > > From: ChiYuan Huang <cy_huang@...htek.com>
> > >
> > > Add Mediatek MT6370 MFD support.
> >
> > No such thing as "MFD support".
> >
> > And you're not getting away with submitting a 370 line patch with a 5
> > word change log either. :)
> >
> > Please at least tell us what the device is and what it's used for.
> 
> I sincerely apologize.
> We will add more descriptions of the MT6370 feature in the v5 patch.
> 
> >
> > > Signed-off-by: ChiYuan Huang <cy_huang@...htek.com>
> > > ---
> > >
> > > v3
> > > - Refine Kconfig help text
> > > - Refine error message of unknown vendor ID in
> > >   mt6370_check_vendor_info()
> > > - Refine return value handling of mt6370_regmap_read()
> > > - Refine all probe error by using dev_err_probe()
> > > - Refine "bank_idx" and "bank_addr" in mt6370_regmap_read() and
> > >   mt6370_regmap_write()
> > > - Add "#define VENID*" and drop the comments in
> > >   mt6370_check_vendor_info()
> > > - Drop "MFD" in MODULE_DESCRIPTION()
> > > ---
> > >  drivers/mfd/Kconfig  |  13 ++
> > >  drivers/mfd/Makefile |   1 +
> > >  drivers/mfd/mt6370.c | 358 +++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  3 files changed, 372 insertions(+)
> > >  create mode 100644 drivers/mfd/mt6370.c

[...]

> > > +static int mt6370_probe(struct i2c_client *i2c)
> > > +{
> > > +     struct mt6370_info *info;
> > > +     struct i2c_client *usbc_i2c;
> > > +     int ret;
> > > +
> > > +     info = devm_kzalloc(&i2c->dev, sizeof(*info), GFP_KERNEL);
> > > +     if (!info)
> > > +             return -ENOMEM;
> > > +
> > > +     info->dev = &i2c->dev;
> > > +
> > > +     usbc_i2c = devm_i2c_new_dummy_device(&i2c->dev, i2c->adapter,
> > > +                                          MT6370_USBC_I2CADDR);
> > > +     if (IS_ERR(usbc_i2c))
> > > +             return dev_err_probe(&i2c->dev, PTR_ERR(usbc_i2c),
> > > +                                  "Failed to register USBC I2C client\n");
> > > +
> > > +     /* Assign I2C client for PMU and TypeC */
> > > +     info->i2c[MT6370_PMU_I2C] = i2c;
> > > +     info->i2c[MT6370_USBC_I2C] = usbc_i2c;
> > > +
> > > +     info->regmap = devm_regmap_init(&i2c->dev, &mt6370_regmap_bus, info,
> > > +                                     &mt6370_regmap_config);
> >
> > Apart from in mt6370_check_vendor_info() where is this actually used?
> 
> Well... from my understanding, we use this MFD driver to make other
> drivers of MT6370 (e.g. charger, ADC, led...) use the same regmap
> settings.
> Thus, this regmap is not only used in mt6370_check_vendor_info().

Well for that to happen you need to store the data somewhere for the
child devices to fetch from.  I don't see that happening in this
patch?  What did I miss?

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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