[PATCH 1/3] iio: adc: ad7768-1: fix one-shot mode data acquisition

[Jonathan Santos]

According to the datasheet, one-shot mode requires a SYNC_IN pulse to
trigger a new sample conversion. In the current implementation, No sync
pulse was sent after switching to one-shot mode and reinit_completion()
was called before mode switching, creating a race condition where spurious
interrupts during mode change could trigger completion prematurely.

Fix by sending a sync pulse after configuring one-shot mode and moving
reinit_completion() after the pulse to ensure it only waits for the
actual conversion completion.

Fixes: a5f8c7da3dbe ("iio: adc: Add AD7768-1 ADC basic support")
Signed-off-by: Jonathan Santos <Jonathan.Santos@xxxxxxxxxx>
---
 drivers/iio/adc/ad7768-1.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index fcd8aea7152e..8d39b71703ae 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -463,12 +463,17 @@ static int ad7768_scan_direct(struct iio_dev *indio_dev)
 	struct ad7768_state *st = iio_priv(indio_dev);
 	int readval, ret;
 
-	reinit_completion(&st->completion);
-
 	ret = ad7768_set_mode(st, AD7768_ONE_SHOT);
 	if (ret < 0)
 		return ret;
 
+	/* One-shot mode requires a SYNC pulse to generate a new sample */
+	ret = ad7768_send_sync_pulse(st);
+	if (ret)
+		return ret;
+
+	reinit_completion(&st->completion);
+
 	ret = wait_for_completion_timeout(&st->completion,
 					  msecs_to_jiffies(1000));
 	if (!ret)
-- 
2.34.1