[PATCH 4.9 033/105] IIO: BME280: Updates to Humidity readings need ctrl_reg write!

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Colin Parker <colin.parker@xxxxxxxxx>

commit 4b1f0c31f96c45e8521dd84aae50f2aa4aecfb7b upstream.

The ctrl_reg register needs to be written after any write to
the humidity registers. The value written to the ctrl_reg register
does not necessarily need to change, but a write operation must
occur.

The regmap_update_bits functions will not write to a register
if the register value matches the value to be written. This saves
unnecessary bus operations.  The change in this patch forces a bus
write during the chip_config operation by switching to
regmap_write_bits.

This will fix issues where the Humidity Sensor Oversampling bits
are not updated after initialization.

Signed-off-by: Colin Parker <colin.parker@xxxxxxxxx>
Acked-by: Andreas Klinger <ak@xxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/iio/pressure/bmp280-core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -558,7 +558,7 @@ static int bmp280_chip_config(struct bmp
 	u8 osrs = BMP280_OSRS_TEMP_X(data->oversampling_temp + 1) |
 		  BMP280_OSRS_PRESS_X(data->oversampling_press + 1);
 
-	ret = regmap_update_bits(data->regmap, BMP280_REG_CTRL_MEAS,
+	ret = regmap_write_bits(data->regmap, BMP280_REG_CTRL_MEAS,
 				 BMP280_OSRS_TEMP_MASK |
 				 BMP280_OSRS_PRESS_MASK |
 				 BMP280_MODE_MASK,