iio: pressure: rohm-bm1390: harden trigger handler against transient errors

bm1390_trigger_handler() returns from three error paths without calling
iio_trigger_notify_done(). The success path at the end does, so on a
transient regmap or read failure the trigger's use_count is never
decremented and iio_trigger_poll_chained() drops subsequent dispatches
until the trigger is reattached.

This is not a fix for a reported bug, only hardening against hardware
or bus glitches; if a glitch is persistent the device is wedged and
needs an unbind anyway, which is left to the user.

Split the function so the inner helper returns bool with the data-read
outcome, and the outer IRQ handler calls iio_trigger_notify_done()
once and reports the result via IRQ_RETVAL().

Signed-off-by: Stepan Ionichev <sozdayvek@gmail.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 16 insertions, 7 deletions

diff --git a/drivers/iio/pressure/rohm-bm1390.c b/drivers/iio/pressure/rohm-bm1390.c
index b3be9de03678..9d72ae64126c 100644
--- a/drivers/iio/pressure/rohm-bm1390.c
+++ b/drivers/iio/pressure/rohm-bm1390.c
@@ -621,17 +621,15 @@ static const struct iio_buffer_setup_ops bm1390_buffer_ops = {
 	.predisable = bm1390_buffer_predisable,
 };
 
-static irqreturn_t bm1390_trigger_handler(int irq, void *p)
+static bool bm1390_handle_trigger(struct iio_dev *idev)
 {
-	struct iio_poll_func *pf = p;
-	struct iio_dev *idev = pf->indio_dev;
 	struct bm1390_data *data = iio_priv(idev);
 	int ret, status;
 
 	/* DRDY is acked by reading status reg */
 	ret = regmap_read(data->regmap, BM1390_REG_STATUS, &status);
 	if (ret || !status)
-		return IRQ_NONE;
+		return false;
 
 	dev_dbg(data->dev, "DRDY trig status 0x%x\n", status);
 
@@ -639,7 +637,7 @@ static irqreturn_t bm1390_trigger_handler(int irq, void *p)
 		ret = bm1390_pressure_read(data, &data->buf.pressure);
 		if (ret) {
 			dev_warn(data->dev, "sample read failed %d\n", ret);
-			return IRQ_NONE;
+			return false;
 		}
 	}
 
@@ -648,15 +646,26 @@ static irqreturn_t bm1390_trigger_handler(int irq, void *p)
 				       &data->buf.temp, sizeof(data->buf.temp));
 		if (ret) {
 			dev_warn(data->dev, "temp read failed %d\n", ret);
-			return IRQ_HANDLED;
+			return true;
 		}
 	}
 
 	iio_push_to_buffers_with_ts(idev, &data->buf, sizeof(data->buf),
 				    data->timestamp);
+
+	return true;
+}
+
+static irqreturn_t bm1390_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *idev = pf->indio_dev;
+	bool result;
+
+	result = bm1390_handle_trigger(idev);
 	iio_trigger_notify_done(idev->trig);
 
-	return IRQ_HANDLED;
+	return IRQ_RETVAL(result);
 }
 
 /* Get timestamps and wake the thread if we need to read data */