[PATCH] iio: dac: mcp4922: fix error handling in mcp4922_write_raw

From: Marcus Folkesson <marcus.folkesson@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>,
	Hartmut Knaack <knaack.h@gmx.de>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
	Marcus Folkesson <marcus.folkesson@gmail.com>
Subject: [PATCH] iio: dac: mcp4922: fix error handling in mcp4922_write_raw
Date: Fri, 24 Aug 2018 22:24:40 +0200	[thread overview]
Message-ID: <20180824202440.21754-1-marcus.folkesson@gmail.com> (raw)

Do not try to write negative values and make sure that the write goes well.

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
---
 drivers/iio/dac/mcp4922.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/dac/mcp4922.c b/drivers/iio/dac/mcp4922.c
index bf9aa3fc0534..b5190d1dae8e 100644
--- a/drivers/iio/dac/mcp4922.c
+++ b/drivers/iio/dac/mcp4922.c
@@ -94,17 +94,22 @@ static int mcp4922_write_raw(struct iio_dev *indio_dev,
 		long mask)
 {
 	struct mcp4922_state *state = iio_priv(indio_dev);
+	int ret;
 
 	if (val2 != 0)
 		return -EINVAL;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
-		if (val > GENMASK(chan->scan_type.realbits-1, 0))
+		if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0))
 			return -EINVAL;
 		val <<= chan->scan_type.shift;
-		state->value[chan->channel] = val;
-		return mcp4922_spi_write(state, chan->channel, val);
+
+		ret = mcp4922_spi_write(state, chan->channel, val);
+		if (!ret)
+			state->value[chan->channel] = val;
+		return ret;
+
 	default:
 		return -EINVAL;
 	}
-- 
2.18.0

