iio: pressure: dps310: Reset chip if MEAS_CFG is corrupt

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 <[email protected]>

Reviewed-by Joel Stanley <[email protected]>

---
 drivers/iio/pressure/dps310.c | 188 ++++++++++++++++++----------------
 1 file changed, 99 insertions(+), 89 deletions(-)

drivers/iio/pressure/dps310.c +18 -0

index 36fb7ae0d0a9..c706a8b423b5 100644
@@ -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
+        */

drivers/iio/pressure/dps310.c +61 -90

+}
+
+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

Quoted 2 lines · Eddie James

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 <[email protected]>

Quoted 37 lines

Signed-off-by Eddie James <[email protected]>

Reviewed-by Joel Stanley <[email protected]>

---
  drivers/iio/pressure/dps310.c | 188 ++++++++++++++++++----------------
  1 file changed, 99 insertions(+), 89 deletions(-)

drivers/iio/pressure/dps310.c +23 -0

index 36fb7ae0d0a9..c706a8b423b5 100644
@@ -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)

drivers/iio/pressure/dps310.c static int dps310_get_coefs(struct dps310_data *data) · line 189

Quoted 5 lines

drivers/iio/pressure/dps310.c +5 -0

+               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?

drivers/iio/pressure/dps310.c static int dps310_get_coefs(struct dps310_data *data) · line 199

Quoted 10 lines

drivers/iio/pressure/dps310.c +9 -0

+       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.

Quoted 175 lines

drivers/iio/pressure/dps310.c +61 -90

+}
+
+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

Quoted 1 line · Andy Shevchenko

On Wed, Aug 10, 2022 at 12:12 AM Eddie James <[email protected]> wrote:

Quoted 7 lines

Quoted 7 lines

drivers/iio/pressure/dps310.c +7 -0

+       rc = regmap_write(data->regmap, 0x0e, 0xA5);
+       if (rc)
+               return rc;
+
+       rc = regmap_write(data->regmap, 0x0f, 0x96);
+       if (rc)
+               return rc;

Quoted 3 lines

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.

Quoted 5 lines

drivers/iio/pressure/dps310.c static int dps310_get_coefs(struct dps310_data *data) · line 199

Quoted 5 lines

drivers/iio/pressure/dps310.c +5 -0

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

Quoted 2 lines · Eddie James

Quoted 1 line · Andy Shevchenko

On Wed, Aug 10, 2022 at 12:12 AM Eddie James <[email protected]> wrote:

...

Quoted 11 lines

Quoted 10 lines

drivers/iio/pressure/dps310.c static int dps310_get_coefs(struct dps310_data *data) · line 189

Quoted 7 lines

drivers/iio/pressure/dps310.c +7 -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?

Quoted 2 lines

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.

...

Quoted 5 lines

Quoted 5 lines

drivers/iio/pressure/dps310.c static int dps310_get_coefs(struct dps310_data *data) · line 199

Quoted 5 lines

drivers/iio/pressure/dps310.c +5 -0

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

Ditto.

Quoted 20 lines · On Fri, 19 Aug 2022 12:42:00 +0300 Andy Shevchenko <[email protected]>…

Quoted 2 lines · Eddie James

Quoted 1 line · Andy Shevchenko

On Wed, Aug 10, 2022 at 12:12 AM Eddie James <[email protected]> wrote:

...

Quoted 7 lines

Quoted 7 lines

Quoted 7 lines

drivers/iio/pressure/dps310.c +7 -0

+       rc = regmap_write(data->regmap, 0x0e, 0xA5);
+       if (rc)
+               return rc;
+
+       rc = regmap_write(data->regmap, 0x0f, 0x96);
+       if (rc)
+               return rc;

Quoted 5 lines

Quoted 3 lines

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.

Quoted 2 lines

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.

Quoted 10 lines

...

Quoted 5 lines

Quoted 5 lines

drivers/iio/pressure/dps310.c static int dps310_get_coefs(struct dps310_data *data) · line 199

Quoted 5 lines

drivers/iio/pressure/dps310.c +5 -0

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

Ditto.

Quoted 23 lines · Jonathan Cameron

Quoted 20 lines · On Fri, 19 Aug 2022 12:42:00 +0300 Andy Shevchenko <[email protected]>…

Quoted 2 lines · Eddie James

Quoted 1 line · Andy Shevchenko

On Wed, Aug 10, 2022 at 12:12 AM Eddie James <[email protected]> wrote:

...

Quoted 7 lines

Quoted 7 lines

Quoted 7 lines

drivers/iio/pressure/dps310.c +7 -0

+       rc = regmap_write(data->regmap, 0x0e, 0xA5);
+       if (rc)
+               return rc;
+
+       rc = regmap_write(data->regmap, 0x0f, 0x96);
+       if (rc)
+               return rc;  

Quoted 5 lines

Quoted 3 lines

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.

Quoted 7 lines

Quoted 2 lines

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

Quoted 10 lines

Quoted 10 lines

...

Quoted 5 lines

Quoted 5 lines

drivers/iio/pressure/dps310.c static int dps310_get_coefs(struct dps310_data *data) · line 199

Quoted 5 lines

drivers/iio/pressure/dps310.c +5 -0

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

Ditto.

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.

drivers/iio/pressure/dps310.c +33 -8

+       /* 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);
+
+               /*

        rc = dps310_read_temp_ready(data);

Quoted 4 lines · 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.

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

...

drivers/iio/pressure/dps310.c static int dps310_get_temp_k(struct dps310_data *data) · line 406

Quoted 11 lines

drivers/iio/pressure/dps310.c +11 -0

+/*
+ * 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.

Quoted 51 lines

drivers/iio/pressure/dps310.c +33 -8

+       /* 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);
+
+               /*

drivers/iio/pressure/dps310.c static int dps310_read_pres_raw(struct dps310_data *data) · line 464

Quoted 10 lines

drivers/iio/pressure/dps310.c +10 -0

+                * 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.

drivers/iio/pressure/dps310.c static int dps310_read_temp_raw(struct dps310_data *data) · line 510

Quoted 7 lines

drivers/iio/pressure/dps310.c +3 -0

+       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.

drivers/iio/pressure/dps310.c static int dps310_read_temp_raw(struct dps310_data *data) · line 521

Quoted 11 lines

drivers/iio/pressure/dps310.c +11 -0

+               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'?

Review

Quoted 3 lines

(quoted diff) +2 -0

+                       goto done;
+       }

As per above.

Quoted 1 line

         rc = dps310_read_temp_ready(data);

Quoted 5 lines · Andy Shevchenko

Quoted 4 lines · 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.

Quoted 1 line

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.