Le 08/02/2021 à 15:27, Wilfried Wessner a écrit :
> 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 <wilfried.wessner@xxxxxxxxx>
>
> ---
>
> The issue was found in combination of an AD7682 ADC with an ARM based
> iMX7-CPU. The SPI line was analyzed with a logic analyzer and a
> discrepancy between applied voltage level and the ADC reported value
> in user space was observed. Digging into the driver code revealed an
> improper mask used for the ADC-result.
>
>
> 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[] = {
> {
Hi,
Thank you for the fix. :)
Reviewed-by: Charles-Antoine Couret <charles-antoine.couret@xxxxxxxxxxxxx>
Regards,
Charles-Antoine Couret
