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SubjectRe: [PATCH v2 2/3] iio: dps310: Temperature measurement errata
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On 5/8/19 10:09 PM, Matt Ranostay wrote:
> 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


Thats correct. These don't show up in the data sheet so I left them as
raw values. Chris, do you know what the source for these values was?

Thanks,

Eddie


>
>> 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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