patch "iio: dac: ad5686: fix bit shift read register" added to staging-next

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    iio: dac: ad5686: fix bit shift read register

to my staging git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-next branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release
during the merge window.

If you have any questions about this process, please let me know.


>From 0e76df5c978338f3051e5126fc0c4245c57a307a Mon Sep 17 00:00:00 2001
From: Mircea Caprioru <mircea.caprioru@analog.com>
Date: Thu, 6 Dec 2018 15:53:15 +0200
Subject: iio: dac: ad5686: fix bit shift read register

This patch solves the register readback issue with the bit shift. When the
dac resolution was lower than the register size (ex. 12 bits out of 16
bits) the readback value was not shifted with the difference in bits and
the value was higher. Also a mask is applied on the read value in order to
get the value relative to the actual bit size.

Fixes: 0357e488b8 ("iio:dac:ad5686: Refactor the driver")
Signed-off-by: Mircea Caprioru <mircea.caprioru@analog.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/iio/dac/ad5686.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
index 54ff76b93366..a332b93ca2c4 100644
--- a/drivers/iio/dac/ad5686.c
+++ b/drivers/iio/dac/ad5686.c
@@ -128,7 +128,8 @@ static int ad5686_read_raw(struct iio_dev *indio_dev,
 		mutex_unlock(&indio_dev->mlock);
 		if (ret < 0)
 			return ret;
-		*val = ret;
+		*val = (ret >> chan->scan_type.shift) &
+			GENMASK(chan->scan_type.realbits - 1, 0);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		*val = st->vref_mv;
-- 
2.20.0