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References: <20220809211246.251006-1-eajames@linux.ibm.com> <20220809211246.251006-2-eajames@linux.ibm.com>
In-Reply-To: <20220809211246.251006-2-eajames@linux.ibm.com>
From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Sat, 13 Aug 2022 01:03:54 +0300
Message-ID: <CAHp75Vf5wcabm_-oKGN2m7z=L2xu1D6wtzKLhu6n19Uhq8yijQ@mail.gmail.com>
Subject: Re: [PATCH v4 1/2] iio: pressure: dps310: Refactor startup procedure
To:     Eddie James <eajames@linux.ibm.com>
Cc:     linux-iio <linux-iio@vger.kernel.org>,
        Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Joel Stanley <joel@jms.id.au>
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Precedence: bulk

On Wed, Aug 10, 2022 at 12:12 AM Eddie James <eajames@linux.ibm.com> wrote:
>
> Move the startup procedure into a function, and correct a missing
> check on the return code for writing the PRS_CFG register.

Code looks good, one remark below.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Signed-off-by: Eddie James <eajames@linux.ibm.com>
> Reviewed-by: Joel Stanley <joel@jms.id.au>
> ---
>  drivers/iio/pressure/dps310.c | 188 ++++++++++++++++++----------------
>  1 file changed, 99 insertions(+), 89 deletions(-)
>
> diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
> index 36fb7ae0d0a9..c706a8b423b5 100644
> --- a/drivers/iio/pressure/dps310.c
> +++ b/drivers/iio/pressure/dps310.c
> @@ -159,6 +159,102 @@ static int dps310_get_coefs(struct dps310_data *data)
>         return 0;
>  }
>
> +/*
> + * Some versions of the chip will read temperatures in the ~60C range when
> + * it's actually ~20C. This is the manufacturer recommended workaround
> + * to correct the issue. The registers used below are undocumented.
> + */
> +static int dps310_temp_workaround(struct dps310_data *data)
> +{
> +       int rc;
> +       int reg;
> +
> +       rc = regmap_read(data->regmap, 0x32, &reg);
> +       if (rc)
> +               return rc;
> +
> +       /*
> +        * If bit 1 is set then the device is okay, and the workaround does not
> +        * need to be applied
> +        */
> +       if (reg & BIT(1))
> +               return 0;
> +
> +       rc = regmap_write(data->regmap, 0x0e, 0xA5);
> +       if (rc)
> +               return rc;
> +
> +       rc = regmap_write(data->regmap, 0x0f, 0x96);
> +       if (rc)
> +               return rc;

This code already exists, but still want to ask, is it really
byte-registers here and not be16/le16 one? In such a case perhaps bulk
write can be used to reflect it better?

> +       rc = regmap_write(data->regmap, 0x62, 0x02);
> +       if (rc)
> +               return rc;
> +
> +       rc = regmap_write(data->regmap, 0x0e, 0x00);
> +       if (rc)
> +               return rc;
> +
> +       return regmap_write(data->regmap, 0x0f, 0x00);

Ditto.

> +}
> +
> +static int dps310_startup(struct dps310_data *data)
> +{
> +       int rc;
> +       int ready;
> +
> +       /*
> +        * Set up pressure sensor in single sample, one measurement per second
> +        * mode
> +        */
> +       rc = regmap_write(data->regmap, DPS310_PRS_CFG, 0);
> +       if (rc)
> +               return rc;
> +
> +       /*
> +        * Set up external (MEMS) temperature sensor in single sample, one
> +        * measurement per second mode
> +        */
> +       rc = regmap_write(data->regmap, DPS310_TMP_CFG, DPS310_TMP_EXT);
> +       if (rc)
> +               return rc;
> +
> +       /* Temp and pressure shifts are disabled when PRC <= 8 */
> +       rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
> +                              DPS310_PRS_SHIFT_EN | DPS310_TMP_SHIFT_EN, 0);
> +       if (rc)
> +               return rc;
> +
> +       /* MEAS_CFG doesn't update correctly unless first written with 0 */
> +       rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
> +                              DPS310_MEAS_CTRL_BITS, 0);
> +       if (rc)
> +               return rc;
> +
> +       /* Turn on temperature and pressure measurement in the background */
> +       rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
> +                              DPS310_MEAS_CTRL_BITS, DPS310_PRS_EN |
> +                              DPS310_TEMP_EN | DPS310_BACKGROUND);
> +       if (rc)
> +               return rc;
> +
> +       /*
> +        * Calibration coefficients required for reporting temperature.
> +        * They are available 40ms after the device has started
> +        */
> +       rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
> +                                     ready & DPS310_COEF_RDY, 10000, 40000);
> +       if (rc)
> +               return rc;
> +
> +       rc = dps310_get_coefs(data);
> +       if (rc)
> +               return rc;
> +
> +       return dps310_temp_workaround(data);
> +}
> +
>  static int dps310_get_pres_precision(struct dps310_data *data)
>  {
>         int rc;
> @@ -677,52 +773,12 @@ static const struct iio_info dps310_info = {
>         .write_raw = dps310_write_raw,
>  };
>
> -/*
> - * Some verions of chip will read temperatures in the ~60C range when
> - * its actually ~20C. This is the manufacturer recommended workaround
> - * to correct the issue. The registers used below are undocumented.
> - */
> -static int dps310_temp_workaround(struct dps310_data *data)
> -{
> -       int rc;
> -       int reg;
> -
> -       rc = regmap_read(data->regmap, 0x32, &reg);
> -       if (rc < 0)
> -               return rc;
> -
> -       /*
> -        * If bit 1 is set then the device is okay, and the workaround does not
> -        * need to be applied
> -        */
> -       if (reg & BIT(1))
> -               return 0;
> -
> -       rc = regmap_write(data->regmap, 0x0e, 0xA5);
> -       if (rc < 0)
> -               return rc;
> -
> -       rc = regmap_write(data->regmap, 0x0f, 0x96);
> -       if (rc < 0)
> -               return rc;
> -
> -       rc = regmap_write(data->regmap, 0x62, 0x02);
> -       if (rc < 0)
> -               return rc;
> -
> -       rc = regmap_write(data->regmap, 0x0e, 0x00);
> -       if (rc < 0)
> -               return rc;
> -
> -       return regmap_write(data->regmap, 0x0f, 0x00);
> -}
> -
>  static int dps310_probe(struct i2c_client *client,
>                         const struct i2c_device_id *id)
>  {
>         struct dps310_data *data;
>         struct iio_dev *iio;
> -       int rc, ready;
> +       int rc;
>
>         iio = devm_iio_device_alloc(&client->dev,  sizeof(*data));
>         if (!iio)
> @@ -747,54 +803,8 @@ static int dps310_probe(struct i2c_client *client,
>         if (rc)
>                 return rc;
>
> -       /*
> -        * Set up pressure sensor in single sample, one measurement per second
> -        * mode
> -        */
> -       rc = regmap_write(data->regmap, DPS310_PRS_CFG, 0);
> -
> -       /*
> -        * Set up external (MEMS) temperature sensor in single sample, one
> -        * measurement per second mode
> -        */
> -       rc = regmap_write(data->regmap, DPS310_TMP_CFG, DPS310_TMP_EXT);
> -       if (rc < 0)
> -               return rc;
> -
> -       /* Temp and pressure shifts are disabled when PRC <= 8 */
> -       rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
> -                              DPS310_PRS_SHIFT_EN | DPS310_TMP_SHIFT_EN, 0);
> -       if (rc < 0)
> -               return rc;
> -
> -       /* MEAS_CFG doesn't update correctly unless first written with 0 */
> -       rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
> -                              DPS310_MEAS_CTRL_BITS, 0);
> -       if (rc < 0)
> -               return rc;
> -
> -       /* Turn on temperature and pressure measurement in the background */
> -       rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
> -                              DPS310_MEAS_CTRL_BITS, DPS310_PRS_EN |
> -                              DPS310_TEMP_EN | DPS310_BACKGROUND);
> -       if (rc < 0)
> -               return rc;
> -
> -       /*
> -        * Calibration coefficients required for reporting temperature.
> -        * They are available 40ms after the device has started
> -        */
> -       rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
> -                                     ready & DPS310_COEF_RDY, 10000, 40000);
> -       if (rc < 0)
> -               return rc;
> -
> -       rc = dps310_get_coefs(data);
> -       if (rc < 0)
> -               return rc;
> -
> -       rc = dps310_temp_workaround(data);
> -       if (rc < 0)
> +       rc = dps310_startup(data);
> +       if (rc)
>                 return rc;
>
>         rc = devm_iio_device_register(&client->dev, iio);
> --
> 2.31.1
>


-- 
With Best Regards,
Andy Shevchenko