iio: light: as73211: fix channel handling in only-color triggered buffer

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.

Add available_scan_masks for all channels and only-color channels to let
the IIO core demux and repack the enabled channels.

Cc: [email protected]
Fixes: 403e558 ("iio: light: as73211: New driver")
Tested-by: Christian Eggers <[email protected]>
Signed-off-by: Javier Carrasco <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jonathan Cameron <[email protected]>

Author: javiercarrascocruz

drivers/iio/light/as73211.c

@@ -177,6 +177,12 @@ struct as73211_data {
 	BIT(AS73211_SCAN_INDEX_TEMP) | \
 	AS73211_SCAN_MASK_COLOR)
 
+static const unsigned long as73211_scan_masks[] = {
+	AS73211_SCAN_MASK_COLOR,
+	AS73211_SCAN_MASK_ALL,
+	0
+};
+
 static const struct iio_chan_spec as73211_channels[] = {
 	{
 		.type = IIO_TEMP,
@@ -672,19 +678,28 @@ 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) {
 		/*
 		 * 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));
@@ -758,6 +773,7 @@ static int as73211_probe(struct i2c_client *client)
 	indio_dev->channels = data->spec_dev->channels;
 	indio_dev->num_channels = data->spec_dev->num_channels;
 	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->available_scan_masks = as73211_scan_masks;
 
 	ret = i2c_smbus_read_byte_data(data->client, AS73211_REG_OSR);
 	if (ret < 0)