3.5.7.31 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Beomho Seo <beomho.seo@xxxxxxxxxxx> commit bef44abccb2677e8d16e50b75316d4fd1061be81 upstream. This effects the reported scale of the raw values, and thus userspace applications that use this value. One micro tesla equal 0.01 gauss. So I have fixed calculation formula And add RAW_TO_GAUSS macro. ASA is in the range of 0 to 255. If multiply 0.003, calculation result(in_magn_[*]_scale) is always 0. So multiply 3000 and return and IIO_VAL_INT_PLUS_MICRO. As a result, read_raw call back function return accurate scale value. Signed-off-by: Beomho Seo <beomho.seo@xxxxxxxxxxx> Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx> [ luis: backported to 3.5: ak8975 driver is in staging, adjusted file name ] Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx> --- drivers/staging/iio/magnetometer/ak8975.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/staging/iio/magnetometer/ak8975.c b/drivers/staging/iio/magnetometer/ak8975.c index 5834e4a..575256b 100644 --- a/drivers/staging/iio/magnetometer/ak8975.c +++ b/drivers/staging/iio/magnetometer/ak8975.c @@ -82,6 +82,7 @@ */ #define AK8975_MAX_CONVERSION_TIMEOUT 500 #define AK8975_CONVERSION_DONE_POLL_TIME 10 +#define RAW_TO_GAUSS(asa) ((((asa) + 128) * 3000) / 256) /* * Per-instance context data for the device. @@ -223,15 +224,15 @@ static int ak8975_setup(struct i2c_client *client) * * Since 1uT = 100 gauss, our final scale factor becomes: * - * Hadj = H * ((ASA + 128) / 256) * 3/10 * 100 - * Hadj = H * ((ASA + 128) * 30 / 256 + * Hadj = H * ((ASA + 128) / 256) * 3/10 * 1/100 + * Hadj = H * ((ASA + 128) * 0.003) / 256 * * Since ASA doesn't change, we cache the resultant scale factor into the * device context in ak8975_setup(). */ - data->raw_to_gauss[0] = ((data->asa[0] + 128) * 30) >> 8; - data->raw_to_gauss[1] = ((data->asa[1] + 128) * 30) >> 8; - data->raw_to_gauss[2] = ((data->asa[2] + 128) * 30) >> 8; + data->raw_to_gauss[0] = RAW_TO_GAUSS(data->asa[0]); + data->raw_to_gauss[1] = RAW_TO_GAUSS(data->asa[1]); + data->raw_to_gauss[2] = RAW_TO_GAUSS(data->asa[2]); return 0; } @@ -434,8 +435,9 @@ static int ak8975_read_raw(struct iio_dev *indio_dev, case IIO_CHAN_INFO_RAW: return ak8975_read_axis(indio_dev, chan->address, val); case IIO_CHAN_INFO_SCALE: - *val = data->raw_to_gauss[chan->address]; - return IIO_VAL_INT; + *val = 0; + *val2 = data->raw_to_gauss[chan->address]; + return IIO_VAL_INT_PLUS_MICRO; } return -EINVAL; } -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html