[PATCH] iio:proximity:sx9324: Fix hardware gain read/write

[Stephen Boyd <swboyd@chromium.org>]

There are four possible gain values according to sx9324_gain_vals[]: 1,
2, 4, and 8. When writing and reading the register the values are off by
one. The bits should be set according to this equation:

	ilog2(<gain>) + 1

so that a gain of 8 is 0x3 in the register field and a gain of 4 is 0x2
in the register field, etc. Fix up the functions.

Fixes: 4c18a890dff8 ("iio:proximity:sx9324: Add SX9324 support")
Cc: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---
 drivers/iio/proximity/sx9324.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/proximity/sx9324.c b/drivers/iio/proximity/sx9324.c
index 0d9bbbb50cb4..a3c8e02f5a56 100644
--- a/drivers/iio/proximity/sx9324.c
+++ b/drivers/iio/proximity/sx9324.c
@@ -379,7 +379,10 @@ static int sx9324_read_gain(struct sx_common_data *data,
 	if (ret)
 		return ret;
 
-	*val = 1 << FIELD_GET(SX9324_REG_PROX_CTRL0_GAIN_MASK, regval);
+	regval = FIELD_GET(SX9324_REG_PROX_CTRL0_GAIN_MASK, regval);
+	if (regval)
+		regval--;
+	*val = 1 << regval;
 
 	return IIO_VAL_INT;
 }
@@ -725,7 +728,7 @@ static int sx9324_write_gain(struct sx_common_data *data,
 	unsigned int gain, reg;
 	int ret;
 
-	gain = ilog2(val);
+	gain = ilog2(val) + 1;
 	reg = SX9324_REG_PROX_CTRL0 + chan->channel / 2;
 	gain = FIELD_PREP(SX9324_REG_PROX_CTRL0_GAIN_MASK, gain);
 

base-commit: a8ee3b32f5da6c77a5ccc0e42c2250d61ba54fe0
-- 
https://chromeos.dev