linux-kernel - [PATCH v2 2/5] iio: adc: ad7606: use realbits for sign-extending in scan

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Message-ID: <20241025095939.271811-3-aardelean@baylibre.com>
Date: Fri, 25 Oct 2024 12:59:36 +0300
From: Alexandru Ardelean <aardelean@...libre.com>
To: linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Cc: jic23@...nel.org,
	krzk+dt@...nel.org,
	robh@...nel.org,
	lars@...afoo.de,
	michael.hennerich@...log.com,
	gstols@...libre.com,
	dlechner@...libre.com,
	conor.dooley@...rochip.com,
	Alexandru Ardelean <aardelean@...libre.com>
Subject: [PATCH v2 2/5] iio: adc: ad7606: use realbits for sign-extending in scan_direct

Currently the 'ad7606' driver supports parts with 18 and 16 bits
resolutions.
But when adding support for AD7607 (which has a 14-bit resolution) we
should check for the 'realbits' field, to be able to sign-extend correctly.

Signed-off-by: Alexandru Ardelean <aardelean@...libre.com>
---
 drivers/iio/adc/ad7606.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index ae49f4ba50d9..effb98b4dc77 100644
--- a/drivers/iio/adc/ad7606.c
+++ b/drivers/iio/adc/ad7606.c
@@ -568,7 +568,7 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
 			      int *val)
 {
 	struct ad7606_state *st = iio_priv(indio_dev);
-	unsigned int storagebits = st->chip_info->channels[1].scan_type.storagebits;
+	unsigned int realbits = st->chip_info->channels[1].scan_type.realbits;
 	const struct iio_chan_spec *chan;
 	int ret;
 
@@ -603,15 +603,15 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
 
 	chan = &indio_dev->channels[ch + 1];
 	if (chan->scan_type.sign == 'u') {
-		if (storagebits > 16)
+		if (realbits > 16)
 			*val = st->data.buf32[ch];
 		else
 			*val = st->data.buf16[ch];
 	} else {
-		if (storagebits > 16)
-			*val = sign_extend32(st->data.buf32[ch], 17);
+		if (realbits > 16)
+			*val = sign_extend32(st->data.buf32[ch], realbits - 1);
 		else
-			*val = sign_extend32(st->data.buf16[ch], 15);
+			*val = sign_extend32(st->data.buf16[ch], realbits - 1);
 	}
 
 error_ret:
-- 
2.46.1