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SubjectRe: [PATCH v2 2/3] iio: dps310: Temperature measurement errata
On Thu, May 9, 2019 at 3:36 AM Eddie James <eajames@linux.ibm.com> wrote:
>
> From: Christopher Bostic <cbostic@linux.vnet.ibm.com>
>
> Add a manufacturer's suggested workaround to deal with early revisions
> of chip that don't indicate correct temperature. Readings can be in the
> ~60C range when they should be in the ~20's.
>
> Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
> Signed-off-by: Joel Stanley <joel@jms.id.au>
> Signed-off-by: Eddie James <eajames@linux.ibm.com>
> ---
> drivers/iio/pressure/dps310.c | 51 ++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
> index 7afaa88..c42808e 100644
> --- a/drivers/iio/pressure/dps310.c
> +++ b/drivers/iio/pressure/dps310.c
> @@ -221,6 +221,9 @@ static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
> case DPS310_MEAS_CFG:
> case DPS310_CFG_REG:
> case DPS310_RESET:
> + case 0x0e:
> + case 0x0f:
> + case 0x62:

What is with the magic values? Are they not documented to what they
are, and hence not defining enum values for them?

- Matt

> return true;
> default:
> return false;
> @@ -237,6 +240,7 @@ static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg)
> case DPS310_TMP_B1:
> case DPS310_TMP_B2:
> case DPS310_MEAS_CFG:
> + case 0x32:
> return true;
> default:
> return false;
> @@ -314,7 +318,7 @@ static int dps310_read_raw(struct iio_dev *iio,
> .writeable_reg = dps310_is_writeable_reg,
> .volatile_reg = dps310_is_volatile_reg,
> .cache_type = REGCACHE_RBTREE,
> - .max_register = 0x29,
> + .max_register = 0x62,
> };
>
> static const struct iio_info dps310_info = {
> @@ -322,6 +326,47 @@ static int dps310_read_raw(struct iio_dev *iio,
> .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.
> + */
> +static int dps310_temp_workaround(struct dps310_data *data)
> +{
> + int r, reg;
> +
> + r = regmap_read(data->regmap, 0x32, &reg);
> + if (r < 0)
> + return r;
> +
> + /*
> + * 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;
> +
> + r = regmap_write(data->regmap, 0x0e, 0xA5);
> + if (r < 0)
> + return r;
> +
> + r = regmap_write(data->regmap, 0x0f, 0x96);
> + if (r < 0)
> + return r;
> +
> + r = regmap_write(data->regmap, 0x62, 0x02);
> + if (r < 0)
> + return r;
> +
> + r = regmap_write(data->regmap, 0x0e, 0x00);
> + if (r < 0)
> + return r;
> +
> + r = regmap_write(data->regmap, 0x0f, 0x00);
> +
> + return r;
> +}
> +
> static int dps310_probe(struct i2c_client *client,
> const struct i2c_device_id *id)
> {
> @@ -383,6 +428,10 @@ static int dps310_probe(struct i2c_client *client,
> if (r < 0)
> goto err;
>
> + r = dps310_temp_workaround(data);
> + if (r < 0)
> + return r;
> +
> r = devm_iio_device_register(&client->dev, iio);
> if (r)
> goto err;
> --
> 1.8.3.1
>

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