[PATCH v4 0/2] iio: pressure: dps310: Reset chip if MEAS_CFG is corrupt

[PATCH v4 0/2] iio: pressure: dps310: Reset chip if MEAS_CFG is corrupt

[Eddie James]

Corruption of the MEAS_CFG register has been observed soon after
system boot. In order to recover this scenario, check MEAS_CFG if
measurement isn't ready, and if it's incorrect, reset the DPS310
and execute the startup procedure. Include a patch to move the
startup procedure into a function.

Changes since v3:
 - Don't check regmap* return codes for < 0
 - Fix comment spelling

Changes since v2:
 - Add some comments
 - Fix the clunky control flow

Changes since v1:
 - Separate into two patches
 - Rename 'dps310_verify_meas_cfg' to 'dps310_check_reset_meas_cfg'

Eddie James (2):
  iio: pressure: dps310: Refactor startup procedure
  iio: pressure: dps310: Reset chip if MEAS_CFG is corrupt

 drivers/iio/pressure/dps310.c | 276 +++++++++++++++++++++-------------
 1 file changed, 172 insertions(+), 104 deletions(-)

-- 
2.31.1

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

[Eddie James]

Move the startup procedure into a function, and correct a missing
check on the return code for writing the PRS_CFG register.

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;
+
+	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);
+}
+
+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

[PATCH v4 2/2] iio: pressure: dps310: Reset chip if MEAS_CFG is corrupt

[Eddie James]

Corruption of the MEAS_CFG register has been observed soon after
system boot. In order to recover this scenario, check MEAS_CFG if
measurement isn't ready, and if it's incorrect, reset the DPS310
and execute the startup procedure.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
---
 drivers/iio/pressure/dps310.c | 88 +++++++++++++++++++++++++++++------
 1 file changed, 73 insertions(+), 15 deletions(-)

diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
index c706a8b423b5..3a1aeeea3cdd 100644
--- a/drivers/iio/pressure/dps310.c
+++ b/drivers/iio/pressure/dps310.c
@@ -393,6 +393,44 @@ static int dps310_get_temp_k(struct dps310_data *data)
 	return scale_factors[ilog2(rc)];
 }
 
+/*
+ * Called with lock held. Returns a negative value on error, a positive value
+ * when the device is not ready, and zero when the device is ready.
+ */
+static int dps310_check_reset_meas_cfg(struct dps310_data *data, int ready_bit)
+{
+	int meas_cfg;
+	int rc = regmap_read(data->regmap, DPS310_MEAS_CFG, &meas_cfg);
+
+	if (rc < 0)
+		return rc;
+
+	/* Device is ready, proceed to measurement */
+	if (meas_cfg & ready_bit)
+		return 0;
+
+	/* Device is OK, just not ready */
+	if (meas_cfg & (DPS310_PRS_EN | DPS310_TEMP_EN | DPS310_BACKGROUND))
+		return 1;
+
+	/* DPS310 register state corrupt, better start from scratch */
+	rc = regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
+	if (rc < 0)
+		return rc;
+
+	/* Wait for device chip access: 2.5ms in specification */
+	usleep_range(2500, 12000);
+
+	/* Reinitialize the chip */
+	rc = dps310_startup(data);
+	if (rc)
+		return rc;
+
+	dev_info(&data->client->dev,
+		 "recovered from corrupted MEAS_CFG=%02x\n", meas_cfg);
+	return 1;
+}
+
 static int dps310_read_pres_raw(struct dps310_data *data)
 {
 	int rc;
@@ -405,16 +443,26 @@ static int dps310_read_pres_raw(struct dps310_data *data)
 	if (mutex_lock_interruptible(&data->lock))
 		return -EINTR;
 
-	rate = dps310_get_pres_samp_freq(data);
-	timeout = DPS310_POLL_TIMEOUT_US(rate);
-
-	/* Poll for sensor readiness; base the timeout upon the sample rate. */
-	rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
-				      ready & DPS310_PRS_RDY,
-				      DPS310_POLL_SLEEP_US(timeout), timeout);
-	if (rc)
+	rc = dps310_check_reset_meas_cfg(data, DPS310_PRS_RDY);
+	if (rc < 0)
 		goto done;
 
+	if (rc > 0) {
+		rate = dps310_get_pres_samp_freq(data);
+		timeout = DPS310_POLL_TIMEOUT_US(rate);
+
+		/*
+		 * Poll for sensor readiness; base the timeout upon the sample
+		 * rate.
+		 */
+		rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG,
+					      ready, ready & DPS310_PRS_RDY,
+					      DPS310_POLL_SLEEP_US(timeout),
+					      timeout);
+		if (rc)
+			goto done;
+	}
+
 	rc = regmap_bulk_read(data->regmap, DPS310_PRS_BASE, val, sizeof(val));
 	if (rc < 0)
 		goto done;
@@ -454,16 +502,26 @@ static int dps310_read_temp_raw(struct dps310_data *data)
 	if (mutex_lock_interruptible(&data->lock))
 		return -EINTR;
 
-	rate = dps310_get_temp_samp_freq(data);
-	timeout = DPS310_POLL_TIMEOUT_US(rate);
-
-	/* Poll for sensor readiness; base the timeout upon the sample rate. */
-	rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
-				      ready & DPS310_TMP_RDY,
-				      DPS310_POLL_SLEEP_US(timeout), timeout);
+	rc = dps310_check_reset_meas_cfg(data, DPS310_TMP_RDY);
 	if (rc < 0)
 		goto done;
 
+	if (rc > 0) {
+		rate = dps310_get_temp_samp_freq(data);
+		timeout = DPS310_POLL_TIMEOUT_US(rate);
+
+		/*
+		 * Poll for sensor readiness; base the timeout upon the sample
+		 * rate.
+		 */
+		rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG,
+					      ready, ready & DPS310_TMP_RDY,
+					      DPS310_POLL_SLEEP_US(timeout),
+					      timeout);
+		if (rc < 0)
+			goto done;
+	}
+
 	rc = dps310_read_temp_ready(data);
 
 done:
-- 
2.31.1

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

[Andy Shevchenko]

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?

> +       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
>


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v4 2/2] iio: pressure: dps310: Reset chip if MEAS_CFG is corrupt

[Andy Shevchenko]

On Wed, Aug 10, 2022 at 12:12 AM Eddie James <eajames@linux.ibm.com> wrote:
>
> Corruption of the MEAS_CFG register has been observed soon after
> system boot. In order to recover this scenario, check MEAS_CFG if
> measurement isn't ready, and if it's incorrect, reset the DPS310
> and execute the startup procedure.

Looks like both patches miss the Fixes tag. Can you add them?

...

> +/*
> + * Called with lock held. Returns a negative value on error, a positive value
> + * when the device is not ready, and zero when the device is ready.
> + */
> +static int dps310_check_reset_meas_cfg(struct dps310_data *data, int ready_bit)
> +{
> +       int meas_cfg;

> +       int rc = regmap_read(data->regmap, DPS310_MEAS_CFG, &meas_cfg);
> +
> +       if (rc < 0)
> +               return rc;

Please, split definition and assignment.

> +       /* Device is ready, proceed to measurement */
> +       if (meas_cfg & ready_bit)
> +               return 0;
> +
> +       /* Device is OK, just not ready */
> +       if (meas_cfg & (DPS310_PRS_EN | DPS310_TEMP_EN | DPS310_BACKGROUND))
> +               return 1;
> +
> +       /* DPS310 register state corrupt, better start from scratch */
> +       rc = regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
> +       if (rc < 0)
> +               return rc;
> +
> +       /* Wait for device chip access: 2.5ms in specification */
> +       usleep_range(2500, 12000);
> +
> +       /* Reinitialize the chip */
> +       rc = dps310_startup(data);
> +       if (rc)
> +               return rc;
> +
> +       dev_info(&data->client->dev,
> +                "recovered from corrupted MEAS_CFG=%02x\n", meas_cfg);
> +       return 1;
> +}
> +
>  static int dps310_read_pres_raw(struct dps310_data *data)
>  {
>         int rc;
> @@ -405,16 +443,26 @@ static int dps310_read_pres_raw(struct dps310_data *data)
>         if (mutex_lock_interruptible(&data->lock))
>                 return -EINTR;
>
> -       rate = dps310_get_pres_samp_freq(data);
> -       timeout = DPS310_POLL_TIMEOUT_US(rate);
> -
> -       /* Poll for sensor readiness; base the timeout upon the sample rate. */
> -       rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
> -                                     ready & DPS310_PRS_RDY,
> -                                     DPS310_POLL_SLEEP_US(timeout), timeout);
> -       if (rc)
> +       rc = dps310_check_reset_meas_cfg(data, DPS310_PRS_RDY);
> +       if (rc < 0)
>                 goto done;
>
> +       if (rc > 0) {
> +               rate = dps310_get_pres_samp_freq(data);
> +               timeout = DPS310_POLL_TIMEOUT_US(rate);
> +
> +               /*
> +                * Poll for sensor readiness; base the timeout upon the sample
> +                * rate.
> +                */
> +               rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG,
> +                                             ready, ready & DPS310_PRS_RDY,
> +                                             DPS310_POLL_SLEEP_US(timeout),
> +                                             timeout);
> +               if (rc)
> +                       goto done;
> +       }

If you split the condition body to a helper, it can be rewritten like
(also note special definition for positive returned numbers):

  rc = ..._reset_meas_cfg(...);
  if (rc  == DPS310_MEAS_NOT_READY)
    rc = ..._new_helper_func(...);
  if (rc)
    goto done;

and looking at this it might be worth considering calling that
conditional in the middle in the _reset_meas_cfg(), so the latter will
return either 0 or negative error code.

> +       rc = dps310_check_reset_meas_cfg(data, DPS310_TMP_RDY);
>         if (rc < 0)
>                 goto done;
>
> +       if (rc > 0) {
> +               rate = dps310_get_temp_samp_freq(data);

Okay, I see this function is different, but still you may realize a
helper from below and something like above suggestion can still be
achieved.

> +               timeout = DPS310_POLL_TIMEOUT_US(rate);
> +
> +               /*
> +                * Poll for sensor readiness; base the timeout upon the sample
> +                * rate.
> +                */
> +               rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG,
> +                                             ready, ready & DPS310_TMP_RDY,
> +                                             DPS310_POLL_SLEEP_US(timeout),
> +                                             timeout);
> +               if (rc < 0)

Why out of a sudden ' < 0'?

> +                       goto done;
> +       }

As per above.

>         rc = dps310_read_temp_ready(data);


-- 
With Best Regards,
Andy Shevchenko

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

[Eddie James]

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
>>
>

Re: [PATCH v4 2/2] iio: pressure: dps310: Reset chip if MEAS_CFG is corrupt

[Eddie James]

On 8/12/22 17:13, Andy Shevchenko wrote:
> On Wed, Aug 10, 2022 at 12:12 AM Eddie James <eajames@linux.ibm.com> wrote:
>> Corruption of the MEAS_CFG register has been observed soon after
>> system boot. In order to recover this scenario, check MEAS_CFG if
>> measurement isn't ready, and if it's incorrect, reset the DPS310
>> and execute the startup procedure.
> Looks like both patches miss the Fixes tag. Can you add them?


Well this isn't really a software fix - there's no identifiable bug in 
the driver. Just trying to recover the chip in this observed mystery 
scenario.


>
> ...
>
>> +/*
>> + * Called with lock held. Returns a negative value on error, a positive value
>> + * when the device is not ready, and zero when the device is ready.
>> + */
>> +static int dps310_check_reset_meas_cfg(struct dps310_data *data, int ready_bit)
>> +{
>> +       int meas_cfg;
>> +       int rc = regmap_read(data->regmap, DPS310_MEAS_CFG, &meas_cfg);
>> +
>> +       if (rc < 0)
>> +               return rc;
> Please, split definition and assignment.


Ack.


>
>> +       /* Device is ready, proceed to measurement */
>> +       if (meas_cfg & ready_bit)
>> +               return 0;
>> +
>> +       /* Device is OK, just not ready */
>> +       if (meas_cfg & (DPS310_PRS_EN | DPS310_TEMP_EN | DPS310_BACKGROUND))
>> +               return 1;
>> +
>> +       /* DPS310 register state corrupt, better start from scratch */
>> +       rc = regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
>> +       if (rc < 0)
>> +               return rc;
>> +
>> +       /* Wait for device chip access: 2.5ms in specification */
>> +       usleep_range(2500, 12000);
>> +
>> +       /* Reinitialize the chip */
>> +       rc = dps310_startup(data);
>> +       if (rc)
>> +               return rc;
>> +
>> +       dev_info(&data->client->dev,
>> +                "recovered from corrupted MEAS_CFG=%02x\n", meas_cfg);
>> +       return 1;
>> +}
>> +
>>   static int dps310_read_pres_raw(struct dps310_data *data)
>>   {
>>          int rc;
>> @@ -405,16 +443,26 @@ static int dps310_read_pres_raw(struct dps310_data *data)
>>          if (mutex_lock_interruptible(&data->lock))
>>                  return -EINTR;
>>
>> -       rate = dps310_get_pres_samp_freq(data);
>> -       timeout = DPS310_POLL_TIMEOUT_US(rate);
>> -
>> -       /* Poll for sensor readiness; base the timeout upon the sample rate. */
>> -       rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
>> -                                     ready & DPS310_PRS_RDY,
>> -                                     DPS310_POLL_SLEEP_US(timeout), timeout);
>> -       if (rc)
>> +       rc = dps310_check_reset_meas_cfg(data, DPS310_PRS_RDY);
>> +       if (rc < 0)
>>                  goto done;
>>
>> +       if (rc > 0) {
>> +               rate = dps310_get_pres_samp_freq(data);
>> +               timeout = DPS310_POLL_TIMEOUT_US(rate);
>> +
>> +               /*
>> +                * Poll for sensor readiness; base the timeout upon the sample
>> +                * rate.
>> +                */
>> +               rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG,
>> +                                             ready, ready & DPS310_PRS_RDY,
>> +                                             DPS310_POLL_SLEEP_US(timeout),
>> +                                             timeout);
>> +               if (rc)
>> +                       goto done;
>> +       }
> If you split the condition body to a helper, it can be rewritten like
> (also note special definition for positive returned numbers):
>
>    rc = ..._reset_meas_cfg(...);
>    if (rc  == DPS310_MEAS_NOT_READY)
>      rc = ..._new_helper_func(...);
>    if (rc)
>      goto done;
>
> and looking at this it might be worth considering calling that
> conditional in the middle in the _reset_meas_cfg(), so the latter will
> return either 0 or negative error code.


To be honest that looks more complicated than the way it is now? And I 
don't think I can make it common between the temp and pressure without 
some complicated macro business.


>
>> +       rc = dps310_check_reset_meas_cfg(data, DPS310_TMP_RDY);
>>          if (rc < 0)
>>                  goto done;
>>
>> +       if (rc > 0) {
>> +               rate = dps310_get_temp_samp_freq(data);
> Okay, I see this function is different, but still you may realize a
> helper from below and something like above suggestion can still be
> achieved.
>
>> +               timeout = DPS310_POLL_TIMEOUT_US(rate);
>> +
>> +               /*
>> +                * Poll for sensor readiness; base the timeout upon the sample
>> +                * rate.
>> +                */
>> +               rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG,
>> +                                             ready, ready & DPS310_TMP_RDY,
>> +                                             DPS310_POLL_SLEEP_US(timeout),
>> +                                             timeout);
>> +               if (rc < 0)
> Why out of a sudden ' < 0'?


Good point, I'll fix that.


>
>> +                       goto done;
>> +       }
> As per above.
>
>>          rc = dps310_read_temp_ready(data);
>

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

[Andy Shevchenko]

On Mon, Aug 15, 2022 at 4:42 PM Eddie James <eajames@linux.ibm.com> wrote:
> 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:

...

> >> +       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.

It doesn't look like you got what I was meaning... Or I misunderstood
what you said.

The code above writes two byte values to two sequential registers
which make me think that they are 16-bit registers at offset 0x0e.

...

> >> +       rc = regmap_write(data->regmap, 0x0e, 0x00);
> >> +       if (rc)
> >> +               return rc;
> >> +
> >> +       return regmap_write(data->regmap, 0x0f, 0x00);

Ditto.

-- 
With Best Regards,
Andy Shevchenko

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

[Jonathan Cameron]

On Fri, 19 Aug 2022 12:42:00 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Mon, Aug 15, 2022 at 4:42 PM Eddie James <eajames@linux.ibm.com> wrote:
> > 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:  
> 
> ...
> 
> > >> +       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.  
> 
> It doesn't look like you got what I was meaning... Or I misunderstood
> what you said.
> 
> The code above writes two byte values to two sequential registers
> which make me think that they are 16-bit registers at offset 0x0e.

Given they are undocumented, this is guessing territory.
Probably best to just leave them as is.
You could do a bulk write on an array though as that implies
nothing about what's in the registers -just that they happen
to be next to each other.

> 
> ...
> 
> > >> +       rc = regmap_write(data->regmap, 0x0e, 0x00);
> > >> +       if (rc)
> > >> +               return rc;
> > >> +
> > >> +       return regmap_write(data->regmap, 0x0f, 0x00);  
> 
> Ditto.
> 

Re: [PATCH v4 2/2] iio: pressure: dps310: Reset chip if MEAS_CFG is corrupt

[Jonathan Cameron]

On Mon, 15 Aug 2022 08:59:03 -0500
Eddie James <eajames@linux.ibm.com> wrote:

> On 8/12/22 17:13, Andy Shevchenko wrote:
> > On Wed, Aug 10, 2022 at 12:12 AM Eddie James <eajames@linux.ibm.com> wrote:  
> >> Corruption of the MEAS_CFG register has been observed soon after
> >> system boot. In order to recover this scenario, check MEAS_CFG if
> >> measurement isn't ready, and if it's incorrect, reset the DPS310
> >> and execute the startup procedure.  
> > Looks like both patches miss the Fixes tag. Can you add them?  
> 
> 
> Well this isn't really a software fix - there's no identifiable bug in 
> the driver. Just trying to recover the chip in this observed mystery 
> scenario.

The tag is useful as well for where to backport this to.
Probably just tag the driver introduction.

Your description makes it clear we aren't finding faults in the
driver - just that it didn't cover this undocumented case!

Jonathan

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

[Eddie James]

On 8/20/22 06:49, Jonathan Cameron wrote:
> On Fri, 19 Aug 2022 12:42:00 +0300
> Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
>
>> On Mon, Aug 15, 2022 at 4:42 PM Eddie James <eajames@linux.ibm.com> wrote:
>>> 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:
>> ...
>>
>>>>> +       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.
>> It doesn't look like you got what I was meaning... Or I misunderstood
>> what you said.
>>
>> The code above writes two byte values to two sequential registers
>> which make me think that they are 16-bit registers at offset 0x0e.
> Given they are undocumented, this is guessing territory.
> Probably best to just leave them as is.
> You could do a bulk write on an array though as that implies
> nothing about what's in the registers -just that they happen
> to be next to each other.


Indeed. Is it worth it to switch to bulk write for two 2-byte writes? 
I'm inclined to say no and will leave this as-is for v6, but if you 
think it is, I can switch it.


Thanks,

Eddie


>
>> ...
>>
>>>>> +       rc = regmap_write(data->regmap, 0x0e, 0x00);
>>>>> +       if (rc)
>>>>> +               return rc;
>>>>> +
>>>>> +       return regmap_write(data->regmap, 0x0f, 0x00);
>> Ditto.
>>

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

[Jonathan Cameron]

On Tue, 6 Sep 2022 14:48:20 -0500
Eddie James <eajames@linux.ibm.com> wrote:

> On 8/20/22 06:49, Jonathan Cameron wrote:
> > On Fri, 19 Aug 2022 12:42:00 +0300
> > Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> >  
> >> On Mon, Aug 15, 2022 at 4:42 PM Eddie James <eajames@linux.ibm.com> wrote:  
> >>> 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:  
> >> ...
> >>  
> >>>>> +       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.  
> >> It doesn't look like you got what I was meaning... Or I misunderstood
> >> what you said.
> >>
> >> The code above writes two byte values to two sequential registers
> >> which make me think that they are 16-bit registers at offset 0x0e.  
> > Given they are undocumented, this is guessing territory.
> > Probably best to just leave them as is.
> > You could do a bulk write on an array though as that implies
> > nothing about what's in the registers -just that they happen
> > to be next to each other.  
> 
> 
> Indeed. Is it worth it to switch to bulk write for two 2-byte writes? 
> I'm inclined to say no and will leave this as-is for v6, but if you 
> think it is, I can switch it.
> 

As far as I'm concerned, fine either way.

Jonathan

> 
> Thanks,
> 
> Eddie
> 
> 
> >  
> >> ...
> >>  
> >>>>> +       rc = regmap_write(data->regmap, 0x0e, 0x00);
> >>>>> +       if (rc)
> >>>>> +               return rc;
> >>>>> +
> >>>>> +       return regmap_write(data->regmap, 0x0f, 0x00);  
> >> Ditto.
> >>