linux-kernel - Re: [PATCH v8 2/3] mfd: add Gateworks System Controller core driver

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Date:   Wed, 29 Apr 2020 07:33:19 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Tim Harvey <tharvey@...eworks.com>
Cc:     Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Linux HWMON List <linux-hwmon@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Device Tree Mailing List <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Robert Jones <rjones@...eworks.com>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v8 2/3] mfd: add Gateworks System Controller core driver

On Tue, 28 Apr 2020, Tim Harvey wrote:

> On Tue, Apr 28, 2020 at 2:44 AM Lee Jones <lee.jones@...aro.org> wrote:
> >
> <snip>
> > > +
> > > +static int gsc_probe(struct i2c_client *client)
> > > +{
> > > +     struct device *dev = &client->dev;
> > > +     struct gsc_dev *gsc;
> > > +     int ret;
> > > +     unsigned int reg;
> > > +
> > > +     gsc = devm_kzalloc(dev, sizeof(*gsc), GFP_KERNEL);
> > > +     if (!gsc)
> > > +             return -ENOMEM;
> > > +
> > > +     gsc->dev = &client->dev;
> > > +     gsc->i2c = client;
> > > +     i2c_set_clientdata(client, gsc);
> > > +
> > > +     gsc->bus.reg_write = gsc_regmap_regwrite;
> > > +     gsc->bus.reg_read = gsc_regmap_regread;
> >
> > Why do you need to store these in ddata?
> 
> Lee,
> 
> Thanks for the review!
> 
> I need the remap_bus* for devm_regmap_init() in the hwmon sub-module driver:
> 
> hwmon->regmap = devm_regmap_init(dev, &gsc->bus, gsc->i2c_hwmon,
> &gsc_hwmon_regmap_config);
> 
> Is there something easier I'm missing?

This is an odd setup.  I haven't seen one driver registering another
driver's Regmap call-backs before, related or otherwise.  Normally the
Regmap is setup (initialised) in the parent driver and child drivers
just make use of it.  Here it looks like you are registering 2
separate Regmaps, but using the same call-backs for both, which seems
wrong to me.

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