linux-kernel - [PATCH 4.19 036/422] iio: dac: mcp4922: fix error handling in mcp4922_write

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Message-Id: <20191119051402.331301983@linuxfoundation.org>
Date:   Tue, 19 Nov 2019 06:13:53 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Marcus Folkesson <marcus.folkesson@...il.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 036/422] iio: dac: mcp4922: fix error handling in mcp4922_write_raw

From: Marcus Folkesson <marcus.folkesson@...il.com>

[ Upstream commit 0833627fc3f757a0dca11e2a9c46c96335a900ee ]

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

Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 bf9aa3fc0534e..b5190d1dae8e3 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;
 	}
-- 
2.20.1