linux-kernel - Re: [PATCH v4 3/4] iio: vcnl4000: Add sampling frequency support for VCNL4010/20.

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Message-ID: <20200425165223.0fc0e930@archlinux>
Date:   Sat, 25 Apr 2020 16:52:23 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Mathieu Othacehe <m.othacehe@...il.com>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald <pmeerw@...erw.net>,
        linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 3/4] iio: vcnl4000: Add sampling frequency support
 for VCNL4010/20.

On Tue, 21 Apr 2020 15:22:11 +0300
Andy Shevchenko <andy.shevchenko@...il.com> wrote:

> On Tue, Apr 21, 2020 at 10:56 AM Mathieu Othacehe <m.othacehe@...il.com> wrote:
> >
> > Add sampling frequency support for proximity data on VCNL4010 and VCNL4020
> > chips.  
> 
> Couple of nitpicks below.
> 
> ...
> 
> > +static const int vcnl4010_prox_sampling_frequency[][2] = {
> > +       {1, 950000},
> > +       {3, 906250},
> > +       {7, 812500},
> > +       {16, 625000},
> > +       {31, 250000},
> > +       {62, 500000},
> > +       {125, 0},  
> 
> > +       {250, 0}  
> 
> Leave comma here, potentially helpful if it will be extended.

Hi Andy,

Doesn't particularly matter either way, but given this is a list of the values
supported by the device, very unlikely it will be extended.

Games like trying to share the first part of a longer array between
multiple device types might occur, but those are usually really ugly.

Jonathan

> 
> > +};  
> 
> ...
> 
> > +static int vcnl4010_write_proxy_samp_freq(struct vcnl4000_data *data, int val,
> > +                                         int val2)
> > +{
> > +       int i;
> > +       const int len = ARRAY_SIZE(vcnl4010_prox_sampling_frequency);
> > +
> > +       for (i = 0; i < len; i++) {
> > +               if (val <= vcnl4010_prox_sampling_frequency[i][0])
> > +                       break;
> > +       }
> > +
> > +       if (i == len)
> > +               return -EINVAL;  
> 
> I would refactor this
> 
>   unsigned int i = ARRAY_SIZE(vcnl4010_prox_sampling_frequency);
> 
>   do {
>     if (val > vcnl4010_prox_sampling_frequency[i][0])
>       break;
>   } while (--i);
> 
> You won't need to go full array to return error in this case.
> 
> > +       return i2c_smbus_write_byte_data(data->client, VCNL4010_PROX_RATE, i);
> > +}  
>