iio: dac: mcp4922: fix error handling in mcp4922_write_raw

[ 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@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iio/dac/mcp4922.c b/drivers/iio/dac/mcp4922.c
index 3854d201a5d6c3a05a1a118c03cee4e815314e20..68dd0be1ac0763977e85625756b5e7361c97dd73 100644 (file)
--- 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;
        }