From d9e144cf83dc15514063eda34e12295fb3e7fe0c Mon Sep 17 00:00:00 2001 From: Wilfried Wessner Date: Wed, 31 Mar 2021 02:01:50 +0000 Subject: [PATCH] iio: adc: ad7949: fix wrong ADC result due to incorrect bit mask MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit stable inclusion from stable-5.10.26 commit d894acab284426d1500f84dca4bfc4634711b28a bugzilla: 51363 -------------------------------- 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: 7f40e0614317f ("iio:adc:ad7949: Add AD7949 ADC driver family") Signed-off-by: Wilfried Wessner Reviewed-by: Andy Shevchenko Reviewed-by: Charles-Antoine Couret Cc: Link: https://lore.kernel.org/r/20210208142705.GA51260@ubuntu Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman Signed-off-by: Chen Jun Acked-by:  Weilong Chen Signed-off-by: Zheng Zengkai --- drivers/iio/adc/ad7949.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c index 5d597e5050f6..1b4b3203e428 100644 --- a/drivers/iio/adc/ad7949.c +++ b/drivers/iio/adc/ad7949.c @@ -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[] = { { -- GitLab