linux-kernel - Re: [PATCH v3 4/6] iio: accel: adxl345: Remove single info instances

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Message-ID: <20240325144857.000017fb@Huawei.com>
Date: Mon, 25 Mar 2024 14:48:57 +0000
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Lothar Rubusch <l.rubusch@...il.com>
CC: Jonathan Cameron <jic23@...nel.org>, <lars@...afoo.de>,
	<Michael.Hennerich@...log.com>, <robh+dt@...nel.org>,
	<krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
	<linux-iio@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <eraretuya@...il.com>
Subject: Re: [PATCH v3 4/6] iio: accel: adxl345: Remove single info
 instances

On Sun, 24 Mar 2024 20:06:51 +0100
Lothar Rubusch <l.rubusch@...il.com> wrote:

> On Sun, Mar 24, 2024 at 2:35 PM Jonathan Cameron <jic23@...nel.org> wrote:
> >
> > On Sat, 23 Mar 2024 12:20:28 +0000
> > Lothar Rubusch <l.rubusch@...il.com> wrote:
> >  
> > > Add a common array adxl3x5_chip_info and an enum for
> > > indexing. This allows to remove local redundantly
> > > initialized code in the bus specific modules.
> > >
> > > Signed-off-by: Lothar Rubusch <l.rubusch@...il.com>
> > > ---
> > >  drivers/iio/accel/adxl345.h      |  7 +++++++
> > >  drivers/iio/accel/adxl345_core.c | 12 ++++++++++++
> > >  drivers/iio/accel/adxl345_i2c.c  | 20 +++++---------------
> > >  drivers/iio/accel/adxl345_spi.c  | 20 +++++---------------
> > >  4 files changed, 29 insertions(+), 30 deletions(-)
> > >
> > > diff --git a/drivers/iio/accel/adxl345.h b/drivers/iio/accel/adxl345.h
> > > index 6b84a2cee..de6b1767d 100644
> > > --- a/drivers/iio/accel/adxl345.h
> > > +++ b/drivers/iio/accel/adxl345.h
> > > @@ -26,11 +26,18 @@
> > >   */
> > >  #define ADXL375_USCALE       480000
> > >
> > > +enum adxl345_device_type {
> > > +     ADXL345,
> > > +     ADXL375,
> > > +};
> > > +
> > >  struct adxl345_chip_info {
> > >       const char *name;
> > >       int uscale;
> > >  };
> > >
> > > +extern const struct adxl345_chip_info adxl3x5_chip_info[];
> > > +
> > >  int adxl345_core_probe(struct device *dev, struct regmap *regmap,
> > >                      int (*setup)(struct device*, struct regmap*));
> > >
> > > diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
> > > index 33424edca..e3718d0dd 100644
> > > --- a/drivers/iio/accel/adxl345_core.c
> > > +++ b/drivers/iio/accel/adxl345_core.c
> > > @@ -62,6 +62,18 @@ struct adxl345_data {
> > >               BIT(IIO_CHAN_INFO_SAMP_FREQ),                           \
> > >  }
> > >
> > > +const struct adxl345_chip_info adxl3x5_chip_info[] = {
> > > +     [ADXL345] = {
> > > +             .name = "adxl345",
> > > +             .uscale = ADXL345_USCALE,
> > > +     },
> > > +     [ADXL375] = {
> > > +             .name = "adxl375",
> > > +             .uscale = ADXL375_USCALE,
> > > +     },
> > > +};
> > > +EXPORT_SYMBOL_NS_GPL(adxl3x5_chip_info, IIO_ADXL345);  
> >
> > There is little advantage here form using an array.  I'd just have
> > two exported structures.   Then the name alone is enough in the
> > id tables.  And probably no need for the enum definition.
> >
> > This use of arrays is an old pattern that makes little sense if the
> > IDs have no actual meaning and you aren't supporting lots of different
> > parts.  For 2 parts I'd argue definitely not worth it.
> >  
> 
> Agree. I see your point. I drop the info array enum patch.
> 
> (...)
> 
> Btw. may I ask another question: The adxl345/75 driver is doing the
> configuration
> inside the probe(). Other Analog drivers moved that out into a
> xxx_setup() and call
> this function in the probe(). In general, is it better to keep all
> inside  the probe() or
> separate? I mean, the probe is still quite short, and reading through
> severl call
> hierarchies feels a bit "sparghetti". On the other side I can see a
> certain idea of
> separation of functionality: dedicated chip configuration. Would you
> mind to give
> me a small statement/opinion on this please?

I'd based it on code complexity.
If it's one call (and error handling) to do it then inline makes sense.

If it's  lots of lines, a separate function make sense.

Where the boundary between the two lies is subjective so I tend to
just go with whatever an author prefers.  Note that I'm not keen
to see the noise of refactors if the code lies in this gray area?

Jonathan


>