[PATCH v2] iio: adc: nxp-sar-adc: harden buffer ISR against per-channel read failure

[Stepan Ionichev <sozdayvek@gmail.com>]

nxp_sar_adc_isr_buffer() bails on the first channel-read failure
without calling iio_trigger_notify_done(), so the trigger use_count
is left incremented and iio_trigger_poll_chained() drops subsequent
dispatches until the device is rebound.

Reaching this path means a state machine has gone wrong (driver bug
or the SAR ADC in an unexpected state) rather than a transient bus
issue, so this is hardening rather than a bug fix. If the underlying
condition persists the device is wedged and needs an unbind anyway.

Call iio_trigger_notify_done() on the error exit too, matching the
success path. The nxp_sar_adc_read_notify() duplication is intentional
and avoids a goto label for a two-line bail-out, as suggested by David.

Signed-off-by: Stepan Ionichev <sozdayvek@gmail.com>
---
v2:
- Drop Fixes: and Cc: stable@; this is a state-machine hardening, not
  a user-visible bug fix (Jonathan)
- Reframe the commit message and explain why the failure is not a bus
  issue
- Inline the iio_trigger_notify_done() in the error exit instead of a
  goto label, accepting the small nxp_sar_adc_read_notify() duplication
  (David)

v1: https://lore.kernel.org/all/20260517162346.189-1-sozdayvek@gmail.com/

 drivers/iio/adc/nxp-sar-adc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iio/adc/nxp-sar-adc.c b/drivers/iio/adc/nxp-sar-adc.c
index 9d9f2c76b..1fc839a15 100644
--- a/drivers/iio/adc/nxp-sar-adc.c
+++ b/drivers/iio/adc/nxp-sar-adc.c
@@ -341,6 +341,7 @@ static void nxp_sar_adc_isr_buffer(struct iio_dev *indio_dev)
 		ret = nxp_sar_adc_read_data(info, info->buffered_chan[i]);
 		if (ret < 0) {
 			nxp_sar_adc_read_notify(info);
+			iio_trigger_notify_done(indio_dev->trig);
 			return;
 		}
 
-- 
2.43.0