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    Subject[PATCH 5.15 168/917] iio: dac: ad5446: Fix ad5622_write() return value
    Date
    From: Pekka Korpinen <pekka.korpinen@iki.fi>

    commit 558df982d4ead9cac628153d0d7b60feae05ddc8 upstream.

    On success i2c_master_send() returns the number of bytes written. The
    call from iio_write_channel_info(), however, expects the return value to
    be zero on success.

    This bug causes incorrect consumption of the sysfs buffer in
    iio_write_channel_info(). When writing more than two characters to
    out_voltage0_raw, the ad5446 write handler is called multiple times
    causing unexpected behavior.

    Fixes: 3ec36a2cf0d5 ("iio:ad5446: Add support for I2C based DACs")
    Signed-off-by: Pekka Korpinen <pekka.korpinen@iki.fi>
    Link: https://lore.kernel.org/r/20210929185755.2384-1-pekka.korpinen@iki.fi
    Cc: <Stable@vger.kernel.org>
    Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/iio/dac/ad5446.c | 9 ++++++++-
    1 file changed, 8 insertions(+), 1 deletion(-)

    --- a/drivers/iio/dac/ad5446.c
    +++ b/drivers/iio/dac/ad5446.c
    @@ -531,8 +531,15 @@ static int ad5622_write(struct ad5446_st
    {
    struct i2c_client *client = to_i2c_client(st->dev);
    __be16 data = cpu_to_be16(val);
    + int ret;

    - return i2c_master_send(client, (char *)&data, sizeof(data));
    + ret = i2c_master_send(client, (char *)&data, sizeof(data));
    + if (ret < 0)
    + return ret;
    + if (ret != sizeof(data))
    + return -EIO;
    +
    + return 0;
    }

    /*

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