Re: [PATCH v4 1/2] iio: pressure: dps310: Refactor startup procedure

[Eddie James <eajames@xxxxxxxxxxxxx>]

On 8/12/22 17:03, Andy Shevchenko wrote:
> On Wed, Aug 10, 2022 at 12:12 AM Eddie James <eajames@xxxxxxxxxxxxx> 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@xxxxxxxxx>
>
> > Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxx>
> > Reviewed-by: Joel Stanley <joel@xxxxxxxxx>
> > ---
> >   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?


The temperature and pressure regs are 24 bits big endian, and all the 
rest are 8 bits. I think the existing approach is best.


Thanks Andy!


> > +       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