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From: "Nuno Sá" <nuno.sa@analog.com>
To: <linux-iio@vger.kernel.org>
Cc: Jonathan Cameron <jic23@kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Michael Hennerich <Michael.Hennerich@analog.com>,
	Hartmut Knaack <knaack.h@gmx.de>,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
	<Stable@vger.kernel.org>
Subject: [PATCH v2 1/2] iio: adis16480: Fix scales factors
Date: Mon, 28 Oct 2019 17:33:48 +0100	[thread overview]
Message-ID: <20191028163349.28866-1-nuno.sa@analog.com> (raw)

This patch fixes the scales for the gyroscope, accelerometer and
barometer. The pressure scale was just wrong. For the others, the scale
factors were not taking into account that a 32bit word is being read
from the device.

Fixes: 7abad1063deb ("iio: adis16480: Fix scale factors")
Fixes: 82e7a1b25017 ("iio: imu: adis16480: Add support for ADIS1649x family of devices")
Cc: <Stable@vger.kernel.org>

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
---
Changes in v2:
 * Correct the Fixes tag.

 drivers/iio/imu/adis16480.c | 77 ++++++++++++++++++++-----------------
 1 file changed, 41 insertions(+), 36 deletions(-)

diff --git a/drivers/iio/imu/adis16480.c b/drivers/iio/imu/adis16480.c
index b99d73887c9f..3b53bbb11bfb 100644
--- a/drivers/iio/imu/adis16480.c
+++ b/drivers/iio/imu/adis16480.c
@@ -620,9 +620,13 @@ static int adis16480_read_raw(struct iio_dev *indio_dev,
 			*val2 = (st->chip_info->temp_scale % 1000) * 1000;
 			return IIO_VAL_INT_PLUS_MICRO;
 		case IIO_PRESSURE:
-			*val = 0;
-			*val2 = 4000; /* 40ubar = 0.004 kPa */
-			return IIO_VAL_INT_PLUS_MICRO;
+			/*
+			 * max scale is 1310 mbar
+			 * max raw value is 32767 shifted for 32bits
+			 */
+			*val = 131; /* 1310mbar = 131 kPa */
+			*val2 = 32767 << 16;
+			return IIO_VAL_FRACTIONAL;
 		default:
 			return -EINVAL;
 		}
@@ -783,13 +787,14 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
 		.channels = adis16485_channels,
 		.num_channels = ARRAY_SIZE(adis16485_channels),
 		/*
-		 * storing the value in rad/degree and the scale in degree
-		 * gives us the result in rad and better precession than
-		 * storing the scale directly in rad.
+		 * Typically we do IIO_RAD_TO_DEGREE in the denominator, which
+		 * is exactly the same as IIO_DEGREE_TO_RAD in numerator, since
+		 * it gives better approximation. However, in this case we
+		 * cannot do it since it would not fit in a 32bit variable.
 		 */
-		.gyro_max_val = IIO_RAD_TO_DEGREE(22887),
-		.gyro_max_scale = 300,
-		.accel_max_val = IIO_M_S_2_TO_G(21973),
+		.gyro_max_val = 22887 << 16,
+		.gyro_max_scale = IIO_DEGREE_TO_RAD(300),
+		.accel_max_val = IIO_M_S_2_TO_G(21973 << 16),
 		.accel_max_scale = 18,
 		.temp_scale = 5650, /* 5.65 milli degree Celsius */
 		.int_clk = 2460000,
@@ -799,9 +804,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
 	[ADIS16480] = {
 		.channels = adis16480_channels,
 		.num_channels = ARRAY_SIZE(adis16480_channels),
-		.gyro_max_val = IIO_RAD_TO_DEGREE(22500),
-		.gyro_max_scale = 450,
-		.accel_max_val = IIO_M_S_2_TO_G(12500),
+		.gyro_max_val = 22500 << 16,
+		.gyro_max_scale = IIO_DEGREE_TO_RAD(450),
+		.accel_max_val = IIO_M_S_2_TO_G(12500 << 16),
 		.accel_max_scale = 10,
 		.temp_scale = 5650, /* 5.65 milli degree Celsius */
 		.int_clk = 2460000,
@@ -811,9 +816,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
 	[ADIS16485] = {
 		.channels = adis16485_channels,
 		.num_channels = ARRAY_SIZE(adis16485_channels),
-		.gyro_max_val = IIO_RAD_TO_DEGREE(22500),
-		.gyro_max_scale = 450,
-		.accel_max_val = IIO_M_S_2_TO_G(20000),
+		.gyro_max_val = 22500 << 16,
+		.gyro_max_scale = IIO_DEGREE_TO_RAD(450),
+		.accel_max_val = IIO_M_S_2_TO_G(20000 << 16),
 		.accel_max_scale = 5,
 		.temp_scale = 5650, /* 5.65 milli degree Celsius */
 		.int_clk = 2460000,
@@ -823,9 +828,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
 	[ADIS16488] = {
 		.channels = adis16480_channels,
 		.num_channels = ARRAY_SIZE(adis16480_channels),
-		.gyro_max_val = IIO_RAD_TO_DEGREE(22500),
-		.gyro_max_scale = 450,
-		.accel_max_val = IIO_M_S_2_TO_G(22500),
+		.gyro_max_val = 22500 << 16,
+		.gyro_max_scale = IIO_DEGREE_TO_RAD(450),
+		.accel_max_val = IIO_M_S_2_TO_G(22500 << 16),
 		.accel_max_scale = 18,
 		.temp_scale = 5650, /* 5.65 milli degree Celsius */
 		.int_clk = 2460000,
@@ -835,9 +840,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
 	[ADIS16495_1] = {
 		.channels = adis16485_channels,
 		.num_channels = ARRAY_SIZE(adis16485_channels),
-		.gyro_max_val = IIO_RAD_TO_DEGREE(20000),
-		.gyro_max_scale = 125,
-		.accel_max_val = IIO_M_S_2_TO_G(32000),
+		.gyro_max_val = 20000 << 16,
+		.gyro_max_scale = IIO_DEGREE_TO_RAD(125),
+		.accel_max_val = IIO_M_S_2_TO_G(32000 << 16),
 		.accel_max_scale = 8,
 		.temp_scale = 12500, /* 12.5 milli degree Celsius */
 		.int_clk = 4250000,
@@ -848,9 +853,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
 	[ADIS16495_2] = {
 		.channels = adis16485_channels,
 		.num_channels = ARRAY_SIZE(adis16485_channels),
-		.gyro_max_val = IIO_RAD_TO_DEGREE(18000),
-		.gyro_max_scale = 450,
-		.accel_max_val = IIO_M_S_2_TO_G(32000),
+		.gyro_max_val = 18000 << 16,
+		.gyro_max_scale = IIO_DEGREE_TO_RAD(450),
+		.accel_max_val = IIO_M_S_2_TO_G(32000 << 16),
 		.accel_max_scale = 8,
 		.temp_scale = 12500, /* 12.5 milli degree Celsius */
 		.int_clk = 4250000,
@@ -861,9 +866,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
 	[ADIS16495_3] = {
 		.channels = adis16485_channels,
 		.num_channels = ARRAY_SIZE(adis16485_channels),
-		.gyro_max_val = IIO_RAD_TO_DEGREE(20000),
-		.gyro_max_scale = 2000,
-		.accel_max_val = IIO_M_S_2_TO_G(32000),
+		.gyro_max_val = 20000 << 16,
+		.gyro_max_scale = IIO_DEGREE_TO_RAD(2000),
+		.accel_max_val = IIO_M_S_2_TO_G(32000 << 16),
 		.accel_max_scale = 8,
 		.temp_scale = 12500, /* 12.5 milli degree Celsius */
 		.int_clk = 4250000,
@@ -874,9 +879,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
 	[ADIS16497_1] = {
 		.channels = adis16485_channels,
 		.num_channels = ARRAY_SIZE(adis16485_channels),
-		.gyro_max_val = IIO_RAD_TO_DEGREE(20000),
-		.gyro_max_scale = 125,
-		.accel_max_val = IIO_M_S_2_TO_G(32000),
+		.gyro_max_val = 20000 << 16,
+		.gyro_max_scale = IIO_DEGREE_TO_RAD(125),
+		.accel_max_val = IIO_M_S_2_TO_G(32000 << 16),
 		.accel_max_scale = 40,
 		.temp_scale = 12500, /* 12.5 milli degree Celsius */
 		.int_clk = 4250000,
@@ -887,9 +892,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
 	[ADIS16497_2] = {
 		.channels = adis16485_channels,
 		.num_channels = ARRAY_SIZE(adis16485_channels),
-		.gyro_max_val = IIO_RAD_TO_DEGREE(18000),
-		.gyro_max_scale = 450,
-		.accel_max_val = IIO_M_S_2_TO_G(32000),
+		.gyro_max_val = 18000 << 16,
+		.gyro_max_scale = IIO_DEGREE_TO_RAD(450),
+		.accel_max_val = IIO_M_S_2_TO_G(32000 << 16),
 		.accel_max_scale = 40,
 		.temp_scale = 12500, /* 12.5 milli degree Celsius */
 		.int_clk = 4250000,
@@ -900,9 +905,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
 	[ADIS16497_3] = {
 		.channels = adis16485_channels,
 		.num_channels = ARRAY_SIZE(adis16485_channels),
-		.gyro_max_val = IIO_RAD_TO_DEGREE(20000),
-		.gyro_max_scale = 2000,
-		.accel_max_val = IIO_M_S_2_TO_G(32000),
+		.gyro_max_val = 20000 << 16,
+		.gyro_max_scale = IIO_DEGREE_TO_RAD(2000),
+		.accel_max_val = IIO_M_S_2_TO_G(32000 << 16),
 		.accel_max_scale = 40,
 		.temp_scale = 12500, /* 12.5 milli degree Celsius */
 		.int_clk = 4250000,
-- 
2.23.0


             reply	other threads:[~2019-10-28 16:33 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-28 16:33 Nuno Sá [this message]
2019-10-28 16:33 ` [PATCH v2 2/2] iio: adis16480: Add debugfs_reg_access entry Nuno Sá
2019-11-03 11:58   ` Jonathan Cameron
2019-11-03 11:56 ` [PATCH v2 1/2] iio: adis16480: Fix scales factors Jonathan Cameron

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