linux-kernel - [PATCH 4.13 086/160] IIO: BME280: Updates to Humidity readings need ctrl

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Date:   Tue, 10 Oct 2017 21:50:14 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Colin Parker <colin.parker@...ima.io>,
        Andreas Klinger <ak@...klinger.de>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: [PATCH 4.13 086/160] IIO: BME280: Updates to Humidity readings need ctrl_reg write!

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

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

From: Colin Parker <colin.parker@...ima.io>

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@...ima.io>
Acked-by: Andreas Klinger <ak@...klinger.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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
@@ -573,7 +573,7 @@ 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,