This is a note to let you know that I've just added the patch titled
iio: accel: bma400: Fix the scale min and max macro values
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iio-accel-bma400-fix-the-scale-min-and-max-macro-val.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3fe775f0bf23c61e30726cb7a278878c829f6916
Author: Jagath Jog J <jagathjog1996@xxxxxxxxx>
Date: Thu May 5 19:00:12 2022 +0530
iio: accel: bma400: Fix the scale min and max macro values
[ Upstream commit 747c7cf1592e226d40543231b26502b332d0ea2f ]
Changing the scale macro values to match the bma400 sensitivity
for 1 LSB of all the available ranges.
Fixes: 465c811f1f20 ("iio: accel: Add driver for the BMA400")
Signed-off-by: Jagath Jog J <jagathjog1996@xxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Link: https://lore.kernel.org/r/20220505133021.22362-2-jagathjog1996@xxxxxxxxx
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/iio/accel/bma400.h b/drivers/iio/accel/bma400.h
index c4c8d74155c2..80330c7ce17f 100644
--- a/drivers/iio/accel/bma400.h
+++ b/drivers/iio/accel/bma400.h
@@ -83,8 +83,27 @@
#define BMA400_ACC_ODR_MIN_WHOLE_HZ 25
#define BMA400_ACC_ODR_MIN_HZ 12
-#define BMA400_SCALE_MIN 38357
-#define BMA400_SCALE_MAX 306864
+/*
+ * BMA400_SCALE_MIN macro value represents m/s^2 for 1 LSB before
+ * converting to micro values for +-2g range.
+ *
+ * For +-2g - 1 LSB = 0.976562 milli g = 0.009576 m/s^2
+ * For +-4g - 1 LSB = 1.953125 milli g = 0.019153 m/s^2
+ * For +-16g - 1 LSB = 7.8125 milli g = 0.076614 m/s^2
+ *
+ * The raw value which is used to select the different ranges is determined
+ * by the first bit set position from the scale value, so BMA400_SCALE_MIN
+ * should be odd.
+ *
+ * Scale values for +-2g, +-4g, +-8g and +-16g are populated into bma400_scales
+ * array by left shifting BMA400_SCALE_MIN.
+ * e.g.:
+ * To select +-2g = 9577 << 0 = raw value to write is 0.
+ * To select +-8g = 9577 << 2 = raw value to write is 2.
+ * To select +-16g = 9577 << 3 = raw value to write is 3.
+ */
+#define BMA400_SCALE_MIN 9577
+#define BMA400_SCALE_MAX 76617
#define BMA400_NUM_REGULATORS 2
#define BMA400_VDD_REGULATOR 0
