linux-kernel - Re: [PATCH v8 2/3] regulator: Add devres version of of_regulator_get

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Message-ID: <ZvVS7ITg2t-RIh8C@smile.fi.intel.com>
Date: Thu, 26 Sep 2024 15:26:20 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Chen-Yu Tsai <wenst@...omium.org>
Cc: Ulf Hansson <ulf.hansson@...aro.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Mark Brown <broonie@...nel.org>, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, Douglas Anderson <dianders@...omium.org>,
	Johan Hovold <johan@...nel.org>, Pablo Sun <pablo.sun@...iatek.com>,
	Macpaul Lin <macpaul.lin@...iatek.com>,
	Sebastian Reichel <sebastian.reichel@...labora.com>
Subject: Re: [PATCH v8 2/3] regulator: Add devres version of
 of_regulator_get_optional()

On Thu, Sep 26, 2024 at 04:43:52PM +0800, Chen-Yu Tsai wrote:
> On Wed, Sep 25, 2024 at 6:56 PM Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com> wrote:
> > On Wed, Sep 25, 2024 at 05:38:05PM +0800, Chen-Yu Tsai wrote:

...

> > > +#if IS_ENABLED(CONFIG_OF)
> >
> > Do we really need this?
> 
> What's the point of going through devres_* stuff if we already know
> _of_regulator_get() is going to fail anyway?

With devm_add_action*() this will be other way around and there are plenty of
APIs done this way. The ifdeffery is simply ugly in the code.

> Also, _of_regulator_get() does not have a stub version for !CONFIG_OF.

So, what prevents us from adding it?

> > > +static struct regulator *_devm_of_regulator_get(struct device *dev, struct device_node *node,
> > > +                                             const char *id, int get_type)
> > > +{
> > > +     struct regulator **ptr, *regulator;
> > > +
> > > +     ptr = devres_alloc(devm_regulator_release, sizeof(*ptr), GFP_KERNEL);
> > > +     if (!ptr)
> > > +             return ERR_PTR(-ENOMEM);
> > > +
> > > +     regulator = _of_regulator_get(dev, node, id, get_type);
> > > +     if (!IS_ERR(regulator)) {
> > > +             *ptr = regulator;
> > > +             devres_add(dev, ptr);
> > > +     } else {
> > > +             devres_free(ptr);
> > > +     }
> > > +
> > > +     return regulator;
> >
> > Why not using devm_add_action() / devm_add_action_or_reset()
> > (whichever suits better here)?
> 
> Cargo cult from _devm_regulator_get() in this file. However since this is
> meant to share the same release function, both functions need to use the
> same mechanism.
> 
> I could also argue that this is not an action, but an allocation, and so
> devres_alloc() seems to make more sense.

It's rather matter of the naming of the devm_add_action*() APIs, but again,
we have plenty of APIs using it when it's allocation and not strictly speaking
an action.

> > > +}
> >
> > > +#endif

...

> > > +static inline struct regulator *__must_check devm_of_regulator_get_optional(struct device *dev,
> > > +                                                                         struct device_node *node,
> > > +                                                                         const char *id)
> >
> > I don't know the conventions here, but I find better to have it as
> >
> > static inline __must_check struct regulator *
> > devm_of_regulator_get_optional(struct device *dev, struct device_node *node, const char *id)
> >
> > Similar to other stubs and declarations.
> 
> I don't think there are any conventions. This file already has three types:
> 
> 1. Wrap the line with the function name on the second line
> 2. Wrap the arguments; wrapped arguments aligned to the left parenthesis.
> 3. Wrap the arguments; wrapped arguments aligned with aribtrary number of
>    tabs.
> 
> I prefer the way I have put them.

The way you put it despite relaxed limit is slightly harder to read.
I don't remember many headers that do so-o indented parameters. Besides
your way defers the burden of resplit to the future in case one more parameter
needs to be added which will excess the 100 limit.

Also __must_check is somehow misplaced in my opinion (talking from my
experience and this can be simply checked by grepping other headers).

That said, I prefer the way I suggested or something alike.

-- 
With Best Regards,
Andy Shevchenko