This is a note to let you know that I've just added the patch titled
iio: pressure: bmp280: correct meas_time_us calculation
to my char-misc git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git in the char-misc-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From 0bf1bfde53b30da7fd7f4a6c3db5b8e77888958d Mon Sep 17 00:00:00 2001 From: Achim Gratz Achim.Gratz@Stromeko.DE Date: Sun, 28 Sep 2025 19:26:28 +0200 Subject: 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: 26ccfaa9ddaa ("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 --- drivers/iio/pressure/bmp280-core.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c index c04e8bb4c993..d983ce9c0b99 100644 --- a/drivers/iio/pressure/bmp280-core.c +++ b/drivers/iio/pressure/bmp280-core.c @@ -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 +