linux-kernel - Re: [PATCH v2 2/2] iio: temperature: add driver support for ti tmp117

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Message-ID: <CAHp75Vcmyvi4V2D0cnmobTGHCS_ci2FC=cBF8tEoG9v51o8RmQ@mail.gmail.com>
Date:   Thu, 1 Apr 2021 12:36:51 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Puranjay Mohan <puranjay12@...il.com>
Cc:     Alexandru Ardelean <alexandru.ardelean@...log.com>,
        Jonathan Cameron <jic23@...nel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Hartmut Knaack <knaack.h@....de>,
        linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Lars-Peter Clausen <lars@...afoo.de>
Subject: Re: [PATCH v2 2/2] iio: temperature: add driver support for ti tmp117

On Thu, Apr 1, 2021 at 12:19 PM Puranjay Mohan <puranjay12@...il.com> wrote:
>
> TMP117 is a Digital temperature sensor with integrated NV memory.
>
> Add support for tmp117 driver in iio subsystem.

+ blank line

> Datasheet:-https://www.ti.com/lit/gpn/tmp117

Make it a tag, i.e. remove the following blank line and use a space after colon.

>
> Signed-off-by: Puranjay Mohan <puranjay12@...il.com>

...

> +/*
> + * tmp117.c - Digital temperature sensor with integrated NV memory

It's useless and provokes an unneeded churn when having a file name
inside the file.
Please, drop it for good.

> + *
> + * Copyright (c) 2021 Puranjay Mohan <puranjay12@...il.com>
> + *
> + * Driver for the Texas Instruments TMP117 Temperature Sensor

> + *

Redundant blank line.

> + * (7-bit I2C slave address (0x48 - 0x4B), changeable via ADD pins)
> + *
> + * Note: This driver assumes that the sensor has been calibrated beforehand.
> + */

...

> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>

Missed:
  bitops.h //sign_extend32()
  types.h // s32


> +
> +#include <linux/iio/iio.h>

...

> +struct tmp117_data {
> +       struct i2c_client *client;
> +};

Doesn't make any sense to have a separate structure for just one
pointer member. Use that pointer directly.

...

> +       case IIO_CHAN_INFO_CALIBBIAS:
> +               ret = i2c_smbus_read_word_swapped(data->client,
> +                                       TMP117_REG_TEMP_OFFSET);
> +               if (ret < 0)
> +                       return ret;
> +               *val = ((int16_t)ret * (int32_t)TMP117_RESOLUTION_10UC)
> +                                                               / 10000;

One line

> +               *val2 = ((int16_t)ret * (int32_t)TMP117_RESOLUTION_10UC)
> +                                                               % 10000;

One line.

I'll be honest, I do not like these explicit castings at all. Can you
revisit and try to refactor that you won't need them?
For example, I can't understand how ret can be higher than 16 bit
since we checked on negative values beforehand.

> +               return IIO_VAL_INT_PLUS_MICRO;
> +
> +       case IIO_CHAN_INFO_SCALE:
> +               /* Conversion from 10s of uC to mC
> +                * as IIO reports temperature in mC
> +                */
> +               *val = TMP117_RESOLUTION_10UC / 10000;
> +               *val2 = (TMP117_RESOLUTION_10UC % 10000) * 100;
> +               return IIO_VAL_INT_PLUS_MICRO;

You use 10000 many times, can you give it an appropriate name (via #define)?

...

> +       s16 off;

> +       case IIO_CHAN_INFO_CALIBBIAS:

> +               off = (s16)val;

Redundant explicit casting.

> +               return i2c_smbus_write_word_swapped(data->client,
> +                                               TMP117_REG_TEMP_OFFSET, off);

...

> +static const struct of_device_id tmp117_of_match[] = {
> +       { .compatible = "ti,tmp117", },

> +       { },

No need to comma in terminator line(s).

> +};

-- 
With Best Regards,
Andy Shevchenko