[PATCH v2] staging: iio: addac: adt7316: check SPI write errors in probe

[Hungyu Lin]

The probe function issues three SPI writes to switch the device
from the default I2C protocol to SPI protocol, but ignores their
return values.

Switch the repeated SPI writes to a loop and return an error
if any of them fail, as failing to switch the protocol should
abort the probe.

Signed-off-by: Hungyu Lin <dennylin0707@xxxxxxxxx>
---
Changes in v2:
- Return error instead of just warning
- Clarify that repeated SPI writes are converted to a loop
---
 drivers/staging/iio/addac/adt7316-spi.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/iio/addac/adt7316-spi.c b/drivers/staging/iio/addac/adt7316-spi.c
index f91325d11394..056a4505bf30 100644
--- a/drivers/staging/iio/addac/adt7316-spi.c
+++ b/drivers/staging/iio/addac/adt7316-spi.c
@@ -98,6 +98,7 @@ static int adt7316_spi_probe(struct spi_device *spi_dev)
 		.multi_read = adt7316_spi_multi_read,
 		.multi_write = adt7316_spi_multi_write,
 	};
+	int i, ret;
 
 	/* don't exceed max specified SPI CLK frequency */
 	if (spi_dev->max_speed_hz > ADT7316_SPI_MAX_FREQ_HZ) {
@@ -107,9 +108,11 @@ static int adt7316_spi_probe(struct spi_device *spi_dev)
 	}
 
 	/* switch from default I2C protocol to SPI protocol */
-	adt7316_spi_write(spi_dev, 0, 0);
-	adt7316_spi_write(spi_dev, 0, 0);
-	adt7316_spi_write(spi_dev, 0, 0);
+	for (i = 0; i < 3; i++) {
+		ret = adt7316_spi_write(spi_dev, 0, 0);
+		if (ret)
+			return ret;
+	}
 
 	return adt7316_probe(&spi_dev->dev, &bus, spi_dev->modalias);
 }
-- 
2.34.1