[PATCH v2 2/2] iio: light: as73211: fix channel handling in only-color triggered buffer

[Javier Carrasco <javier.carrasco.cruz@gmail.com>]

The channel index is off by one unit if AS73211_SCAN_MASK_ALL is not
set (optimized path for color channel readings), and it must be shifted
instead of leaving an empty channel for the temperature when it is off.

Once the channel index is fixed, the uninitialized channel must be set
to zero to avoid pushing uninitialized data.

Cc: stable@vger.kernel.org
Fixes: 403e5586b52e ("iio: light: as73211: New driver")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
 drivers/iio/light/as73211.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/light/as73211.c b/drivers/iio/light/as73211.c
index be0068081ebb..2d45dfeda406 100644
--- a/drivers/iio/light/as73211.c
+++ b/drivers/iio/light/as73211.c
@@ -672,9 +672,12 @@ static irqreturn_t as73211_trigger_handler(int irq __always_unused, void *p)
 
 		/* AS73211 starts reading at address 2 */
 		ret = i2c_master_recv(data->client,
-				(char *)&scan.chan[1], 3 * sizeof(scan.chan[1]));
+				(char *)&scan.chan[0], 3 * sizeof(scan.chan[0]));
 		if (ret < 0)
 			goto done;
+
+		/* Avoid pushing uninitialized data */
+		scan.chan[3] = 0;
 	}
 
 	if (data_result) {
@@ -682,9 +685,15 @@ static irqreturn_t as73211_trigger_handler(int irq __always_unused, void *p)
 		 * Saturate all channels (in case of overflows). Temperature channel
 		 * is not affected by overflows.
 		 */
-		scan.chan[1] = cpu_to_le16(U16_MAX);
-		scan.chan[2] = cpu_to_le16(U16_MAX);
-		scan.chan[3] = cpu_to_le16(U16_MAX);
+		if (*indio_dev->active_scan_mask == AS73211_SCAN_MASK_ALL) {
+			scan.chan[1] = cpu_to_le16(U16_MAX);
+			scan.chan[2] = cpu_to_le16(U16_MAX);
+			scan.chan[3] = cpu_to_le16(U16_MAX);
+		} else {
+			scan.chan[0] = cpu_to_le16(U16_MAX);
+			scan.chan[1] = cpu_to_le16(U16_MAX);
+			scan.chan[2] = cpu_to_le16(U16_MAX);
+		}
 	}
 
 	iio_push_to_buffers_with_timestamp(indio_dev, &scan, iio_get_time_ns(indio_dev));

-- 
2.43.0