linux-kernel - [PATCH] iio: cros_ec: Fix gyro scale calculation

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Message-Id: <20190220150300.3302-1-enric.balletbo@collabora.com>
Date:   Wed, 20 Feb 2019 16:03:00 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Jonathan Cameron <jic23@...nel.org>, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Gwendal Grignou <gwendal@...omium.org>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Guenter Roeck <groeck@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        Lars-Peter Clausen <lars@...afoo.de>, kernel@...labora.com,
        Hartmut Knaack <knaack.h@....de>
Subject: [PATCH] iio: cros_ec: Fix gyro scale calculation

From: Gwendal Grignou <gwendal@...omium.org>

Calculation was copied from IIO_DEGREE_TO_RAD, but offset added to avoid
rounding error is wrong. It should be only half of the divider.

Fixes: c14dca07a31d ("iio: cros_ec_sensors: add ChromeOS EC Contiguous Sensors driver")
Signed-off-by: Gwendal Grignou <gwendal@...omium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
---

 drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
index 89cb0066a6e0..600942af9f9c 100644
--- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
+++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
@@ -103,7 +103,7 @@ static int cros_ec_sensors_read(struct iio_dev *indio_dev,
 			 * Do not use IIO_DEGREE_TO_RAD to avoid precision
 			 * loss. Round to the nearest integer.
 			 */
-			*val = div_s64(val64 * 314159 + 9000000ULL, 1000);
+			*val = div_s64(val64 * 314159 + 500ULL, 1000);
 			*val2 = 18000 << (CROS_EC_SENSOR_BITS - 1);
 			ret = IIO_VAL_FRACTIONAL;
 			break;
-- 
2.20.1