Commit 0bf1bfde authored Sep 28, 2025 by Achim Gratz Committed by Jonathan Cameron Oct 13, 2025

iio: pressure: bmp280: correct meas_time_us calculation

Correction of meas_time_us initialization based on an observation and
partial patch by David Lechner.

The constant part of the measurement time (as described in the
datasheet and implemented in the BM(P/E)2 Sensor API) was apparently
forgotten (it was already correctly applied for the BMP380) and is now
used.

There was also another thinko in bmp280_wait_conv:
data->oversampling_humid can actually have a value of 0 (for an
oversampling_ratio of 1), so it can not be used to detect the presence
of the humidity measurement capability.  Use
data->chip_info->oversampling_humid_avail instead, which is NULL for
chips that cannot measure humidity and therefore must skip that part
of the calculation.

Closes: https://lore.kernel.org/linux-iio/875xgfg0wz.fsf@Gerda.invalid/


Fixes: 26ccfaa9 ("iio: pressure: bmp280: Use sleep and forced mode for oneshot captures")
Suggested-by: David Lechner <dlechner@baylibre.com>
Tested-by: Achim Gratz <Achim.Gratz@Stromeko.DE>
Signed-off-by: Achim Gratz <Achim.Gratz@Stromeko.DE>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

parent 8a6b7989

drivers/iio/pressure/bmp280-core.c

+9 −6

Original line number	Diff line number	Diff line
		@@ -1040,13 +1040,16 @@ static int bmp280_wait_conv(struct bmp280_data *data)
		unsigned int reg, meas_time_us;
		int ret;

		/* Check if we are using a BME280 device */
		if (data->oversampling_humid)
		meas_time_us = BMP280_PRESS_HUMID_MEAS_OFFSET +
		BIT(data->oversampling_humid) * BMP280_MEAS_DUR;
		/* Constant part of the measurement time */
		meas_time_us = BMP280_MEAS_OFFSET;

		else
		meas_time_us = 0;
		/*
		* Check if we are using a BME280 device,
		* Humidity measurement time
		*/
		if (data->chip_info->oversampling_humid_avail)
		meas_time_us += BMP280_PRESS_HUMID_MEAS_OFFSET +
		BIT(data->oversampling_humid) * BMP280_MEAS_DUR;

		/* Pressure measurement time */
		meas_time_us += BMP280_PRESS_HUMID_MEAS_OFFSET +