linux-kernel - [PATCH v2 4/6] iio: pressure: Simplify and make more clear temperature readings

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Message-Id: <20240313174007.1934983-5-vassilisamir@gmail.com>
Date: Wed, 13 Mar 2024 18:40:05 +0100
From: Vasileios Amoiridis <vassilisamir@...il.com>
To: jic23@...nel.org
Cc: lars@...afoo.de,
	andriy.shevchenko@...ux.intel.com,
	ang.iglesiasg@...il.com,
	mazziesaccount@...il.com,
	ak@...klinger.de,
	petre.rodan@...dimension.ro,
	linus.walleij@...aro.org,
	phil@...pberrypi.com,
	579lpy@...il.com,
	linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Vasileios Amoiridis <vassilisamir@...il.com>
Subject: [PATCH v2 4/6] iio: pressure: Simplify and make more clear temperature readings

The read_press/read_humid functions need the updated t_fine value
in order to calculate the current pressure/humidity. Temperature
reads should be removed from the read_press/read_humid functions
and should be placed in the oneshot captures before the pressure
and humidity reads. This makes the code more intuitive.

Signed-off-by: Vasileios Amoiridis <vassilisamir@...il.com>
---
 drivers/iio/pressure/bmp280-core.c | 38 ++++++++++++++----------------
 1 file changed, 18 insertions(+), 20 deletions(-)

diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
index 6d7734f867bc..377e90d9e5a2 100644
--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -404,11 +404,6 @@ static u32 bmp280_read_press(struct bmp280_data *data)
 	s32 adc_press;
 	int ret;
 
-	/* Read and compensate temperature so we get a reading of t_fine. */
-	ret = bmp280_read_temp(data);
-	if (ret < 0)
-		return ret;
-
 	ret = regmap_bulk_read(data->regmap, BMP280_REG_PRESS_MSB,
 			       data->buf, sizeof(data->buf));
 	if (ret < 0) {
@@ -433,11 +428,6 @@ static u32 bmp280_read_humid(struct bmp280_data *data)
 	s32 adc_humidity;
 	int ret;
 
-	/* Read and compensate temperature so we get a reading of t_fine. */
-	ret = bmp280_read_temp(data);
-	if (ret < 0)
-		return ret;
-
 	ret = regmap_bulk_read(data->regmap, BMP280_REG_HUMIDITY_MSB,
 			       &data->be16, sizeof(data->be16));
 	if (ret < 0) {
@@ -470,12 +460,21 @@ static int bmp280_read_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_PROCESSED:
 		switch (chan->type) {
 		case IIO_HUMIDITYRELATIVE:
+			/* Read temperature to update the t_fine value */
+			data->chip_info->read_temp(data);
 			ret = data->chip_info->read_humid(data);
 			*val = data->chip_info->humid_coeffs[0] * ret;
 			*val2 = data->chip_info->humid_coeffs[1];
 			ret = IIO_VAL_FRACTIONAL;
 			break;
 		case IIO_PRESSURE:
+			/*
+			 * Read temperature to update the t_fine value.
+			 * BMP5xx devices do this in hardware, so skip it.
+			 */
+			if (strcmp(indio_dev->name, "bmp580"))
+				data->chip_info->read_temp(data);
+
 			ret = data->chip_info->read_press(data);
 			*val = data->chip_info->press_coeffs[0] * ret;
 			*val2 = data->chip_info->press_coeffs[1];
@@ -500,10 +499,19 @@ static int bmp280_read_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_RAW:
 		switch (chan->type) {
 		case IIO_HUMIDITYRELATIVE:
+			/* Read temperature to update the t_fine value */
+			data->chip_info->read_temp(data);
 			*val = data->chip_info->read_humid(data);
 			ret = IIO_VAL_INT;
 			break;
 		case IIO_PRESSURE:
+			/*
+			 * Read temperature to update the t_fine value.
+			 * BMP5xx devices do this in hardware, so skip it.
+			 */
+			if (strcmp(indio_dev->name, "bmp580"))
+				data->chip_info->read_temp(data);
+
 			*val = data->chip_info->read_press(data);
 			ret = IIO_VAL_INT;
 			break;
@@ -1092,11 +1100,6 @@ static u32 bmp380_read_press(struct bmp280_data *data)
 	s32 adc_press;
 	int ret;
 
-	/* Read and compensate for temperature so we get a reading of t_fine */
-	ret = bmp380_read_temp(data);
-	if (ret)
-		return ret;
-
 	ret = regmap_bulk_read(data->regmap, BMP380_REG_PRESS_XLSB,
 			       data->buf, sizeof(data->buf));
 	if (ret) {
@@ -2009,11 +2012,6 @@ static u32 bmp180_read_press(struct bmp280_data *data)
 	s32 adc_press;
 	int ret;
 
-	/* Read and compensate temperature so we get a reading of t_fine. */
-	ret = bmp180_read_temp(data);
-	if (ret)
-		return ret;
-
 	ret = bmp180_read_adc_press(data, &adc_press);
 	if (ret)
 		return ret;
-- 
2.25.1