linux-kernel - Re: [PATCH v4 2/2] iio: adc: ad4130: add AD4130 driver

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Date:   Tue, 14 Jun 2022 12:47:35 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Cosmin Tanislav <demonsingur@...il.com>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Cosmin Tanislav <cosmin.tanislav@...log.com>
Subject: Re: [PATCH v4 2/2] iio: adc: ad4130: add AD4130 driver

On Wed, 8 Jun 2022 23:11:51 +0300
Cosmin Tanislav <demonsingur@...il.com> wrote:

> On 6/8/22 18:59, Andy Shevchenko wrote:
> > On Wed, Jun 8, 2022 at 12:19 PM Cosmin Tanislav <demonsingur@...il.com> wrote:  
> >>
> >> AD4130-8 is an ultra-low power, high precision, measurement solution for
> >> low bandwidth battery operated applications.
> >>
> >> The fully integrated AFE (Analog Front-End) includes a multiplexer for up
> >> to 16 single-ended or 8 differential inputs, PGA (Programmable Gain
> >> Amplifier), 24-bit Sigma-Delta ADC, on-chip reference and oscillator,
> >> selectable filter options, smart sequencer, sensor biasing and excitation
> >> options, diagnostics, and a FIFO buffer.  
> > 
> > I believe we may gain a few LoCs by slightly bending the rule of 80.
> > Also see below.
> >   
> 
> I'll only go over the 80 columns limit if Jonathan agrees to it.


Where it helps readability I fine with us going past 80.
I'm not convinced by every case Andy highlights, but many do
make things easier to read.


> 
> >> +       *size = ad4130_reg_size[reg];
> >> +       if (!*size)
> >> +               return -EINVAL;  
> > 
> > Is this check necessary?
> >   
> 
> Yes. I haven't described all registers in the table, and the registers
> can be accessed by the user via the debugfs_reg_access() method.

For that one, probably worth a comment as not immediately obvious.

> 

...

> 
> >> +       switch (ref_sel) {
> >> +       case AD4130_REF_REFIN1:
> >> +               ret = regulator_get_voltage(st->regulators[2].consumer);
> >> +               break;
> >> +       case AD4130_REF_REFIN2:
> >> +               ret = regulator_get_voltage(st->regulators[3].consumer);
> >> +               break;
> >> +       case AD4130_REF_AVDD_AVSS:
> >> +               ret = regulator_get_voltage(st->regulators[0].consumer);
> >> +               break;
> >> +       case AD4130_REF_REFOUT_AVSS:
> >> +               ret = st->int_ref_uv;
> >> +               break;
> >> +       default:
> >> +               ret = -EINVAL;
> >> +               break;
> >> +       }  
> >   
> >> +       if (ret < 0)
> >> +               return dev_err_probe(dev, ret, "Cannot use reference %u\n",
> >> +                                    ref_sel);  
> > 
> > Can it be moved to the caller where it would cleaner to use, I think?
> > As a good side effect the all above will be shortened to just return directly.
> >   
> 
> I'm pretty sure I remember Jonathan suggested moving it inside the
> function.

It's possible, though I don't know what my reasoning would have been...