From e43dfc4a9c15b92fed8d12d7b4a343824a8aac9b Mon Sep 17 00:00:00 2001 From: =?utf8?q?Uwe=20Kleine-K=C3=B6nig?= Date: Mon, 4 Nov 2024 11:19:04 +0100 Subject: [PATCH] iio: adc: ad7124: Disable all channels at probe time MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit 4be339af334c283a1a1af3cb28e7e448a0aa8a7c upstream. When during a measurement two channels are enabled, two measurements are done that are reported sequencially in the DATA register. As the code triggered by reading one of the sysfs properties expects that only one channel is enabled it only reads the first data set which might or might not belong to the intended channel. To prevent this situation disable all channels during probe. This fixes a problem in practise because the reset default for channel 0 is enabled. So all measurements before the first measurement on channel 0 (which disables channel 0 at the end) might report wrong values. Fixes: 7b8d045e497a ("iio: adc: ad7124: allow more than 8 channels") Reviewed-by: Nuno Sa Signed-off-by: Uwe Kleine-König Link: https://patch.msgid.link/20241104101905.845737-2-u.kleine-koenig@baylibre.com Cc: Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/adc/ad7124.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c index 06a541fa3cfea..93f32bba73f62 100644 --- a/drivers/iio/adc/ad7124.c +++ b/drivers/iio/adc/ad7124.c @@ -856,6 +856,9 @@ static int ad7124_setup(struct ad7124_state *st) * set all channels to this default value. */ ad7124_set_channel_odr(st, i, 10); + + /* Disable all channels to prevent unintended conversions. */ + ad_sd_write_reg(&st->sd, AD7124_CHANNEL(i), 2, 0); } return ret; -- 2.47.3