From 7cdfbc0113d087348b8e65dd79276d0f57b89a10 Mon Sep 17 00:00:00 2001 From: David Lechner Date: Mon, 5 May 2025 13:28:40 -0500 Subject: [PATCH] iio: adc: ad7944: mask high bits on direct read MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Apply a mask to the raw value received over the SPI bus for unsigned direct reads. As we found recently, SPI controllers may not set unused bits to 0 when reading with bits_per_word != {8,16,32}. The ad7944 uses bits_per_word of 14 and 18, so we need to mask the value to be sure we returning the correct value to userspace during a direct read. Fixes: d1efcf8871db ("iio: adc: ad7944: add driver for AD7944/AD7985/AD7986") Signed-off-by: David Lechner Reviewed-by: Nuno Sá Link: https://patch.msgid.link/20250505-iio-adc-ad7944-max-high-bits-on-direct-read-v1-1-b173facceefe@baylibre.com Cc: Signed-off-by: Jonathan Cameron --- drivers/iio/adc/ad7944.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/iio/adc/ad7944.c b/drivers/iio/adc/ad7944.c index 2f949fe558731..37a137bd83571 100644 --- a/drivers/iio/adc/ad7944.c +++ b/drivers/iio/adc/ad7944.c @@ -377,6 +377,8 @@ static int ad7944_single_conversion(struct ad7944_adc *adc, if (chan->scan_type.sign == 's') *val = sign_extend32(*val, chan->scan_type.realbits - 1); + else + *val &= GENMASK(chan->scan_type.realbits - 1, 0); return IIO_VAL_INT; } -- 2.47.2