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iio: adc: ad7949: fix wrong ADC result due to incorrect bit mask 

commit f890987fac8153227258121740a9609668c427f3 upstream.

Fixes a wrong bit mask used for the ADC's result, which was caused by an
improper usage of the GENMASK() macro. The bits higher than ADC's
resolution are undefined and if not masked out correctly, a wrong result
can be given. The GENMASK() macro indexing is zero based, so the mask has
to go from [resolution - 1 , 0].

Fixes: 7f40e06143 ("iio:adc:ad7949: Add AD7949 ADC driver family")
Signed-off-by: Wilfried Wessner <wilfried.wessner@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Charles-Antoine Couret <charles-antoine.couret@essensium.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210208142705.GA51260@ubuntu
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Wilfried Wessner 2021-02-08 15:27:05 +01:00 committed by Greg Kroah-Hartman
parent a605c095bb
commit 4458ae8d40
1 changed files with 1 additions and 1 deletions
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2
drivers/iio/adc/ad7949.c
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@ -91,7 +91,7 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val,
int ret;
int i;
int bits_per_word = ad7949_adc->resolution;
int mask = GENMASK(ad7949_adc->resolution, 0);
int mask = GENMASK(ad7949_adc->resolution - 1, 0);
struct spi_message msg;
struct spi_transfer tx[] = {
{