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Date: Mon, 15 Aug 2022 08:42:56 -0500
From: Eddie James <eajames@...ux.ibm.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: linux-iio <linux-iio@...r.kernel.org>,
Jonathan Cameron <jic23@...nel.org>,
Lars-Peter Clausen <lars@...afoo.de>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Joel Stanley <joel@....id.au>
Subject: Re: [PATCH v4 1/2] iio: pressure: dps310: Refactor startup procedure
On 8/12/22 17:03, Andy Shevchenko wrote:
> On Wed, Aug 10, 2022 at 12:12 AM Eddie James <eajames@...ux.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@...il.com>
>
>> Signed-off-by: Eddie James <eajames@...ux.ibm.com>
>> Reviewed-by: Joel Stanley <joel@....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, ®);
>> + 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, ®);
>> - 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
>>
>
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