Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <e35b595f-572e-a539-c550-831cdd02dbd3@linux.ibm.com>
Date:   Mon, 15 Aug 2022 08:42:56 -0500
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.11.0
Subject: Re: [PATCH v4 1/2] iio: pressure: dps310: Refactor startup procedure
Content-Language: en-US
To:     Andy Shevchenko <andy.shevchenko@gmail.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>
References: <20220809211246.251006-1-eajames@linux.ibm.com>
 <20220809211246.251006-2-eajames@linux.ibm.com>
 <CAHp75Vf5wcabm_-oKGN2m7z=L2xu1D6wtzKLhu6n19Uhq8yijQ@mail.gmail.com>
From:   Eddie James <eajames@linux.ibm.com>
In-Reply-To: <CAHp75Vf5wcabm_-oKGN2m7z=L2xu1D6wtzKLhu6n19Uhq8yijQ@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk


On 8/12/22 17:03, Andy Shevchenko wrote:
> 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?


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
>>
>