[PATCH] iio: light: hid-sensor-als: Avoid failure for chromaticity support

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

With the commit ee3710f39f9d ("iio: hid-sensor-als: Add light chromaticity
support"), there is an assumption that the every HID ALS descriptor has
support of usage ids for chromaticity support. If they are not present,
probe fails for the driver . This breaks ALS functionality on majority of
platforms.

It is possible that chromaticity usage ids are not present. When not
present, restrict number of IIO channels to not include support for
chromaticity and continue.

Fixes: ee3710f39f9d ("iio: hid-sensor-als: Add light chromaticity support")
Reported-by: Thomas Weißschuh <thomas@t-8ch.de>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218223
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: stable@vger.kernel.org
---
 drivers/iio/light/hid-sensor-als.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/light/hid-sensor-als.c b/drivers/iio/light/hid-sensor-als.c
index f17304b54468..9941b0b927c7 100644
--- a/drivers/iio/light/hid-sensor-als.c
+++ b/drivers/iio/light/hid-sensor-als.c
@@ -303,11 +303,14 @@ static int als_parse_report(struct platform_device *pdev,
 				struct hid_sensor_hub_device *hsdev,
 				struct iio_chan_spec *channels,
 				unsigned usage_id,
-				struct als_state *st)
+				struct als_state *st,
+				int *max_channels)
 {
 	int ret;
 	int i;
 
+	*max_channels = CHANNEL_SCAN_INDEX_MAX;
+
 	for (i = 0; i <= CHANNEL_SCAN_INDEX_ILLUM; ++i) {
 		ret = sensor_hub_input_get_attribute_info(hsdev,
 						HID_INPUT_REPORT,
@@ -326,8 +329,12 @@ static int als_parse_report(struct platform_device *pdev,
 				usage_id,
 				HID_USAGE_SENSOR_LIGHT_COLOR_TEMPERATURE,
 				&st->als[CHANNEL_SCAN_INDEX_COLOR_TEMP]);
-	if (ret < 0)
-		return ret;
+	if (ret < 0) {
+		*max_channels = CHANNEL_SCAN_INDEX_ILLUM;
+		ret = 0;
+		goto skip_color_chromaticity;
+	}
+
 	als_adjust_channel_bit_mask(channels, CHANNEL_SCAN_INDEX_COLOR_TEMP,
 				st->als[CHANNEL_SCAN_INDEX_COLOR_TEMP].size);
 
@@ -354,6 +361,7 @@ static int als_parse_report(struct platform_device *pdev,
 			st->als[next_scan_index].report_id);
 	}
 
+skip_color_chromaticity:
 	st->scale_precision = hid_sensor_format_scale(usage_id,
 				&st->als[CHANNEL_SCAN_INDEX_INTENSITY],
 				&st->scale_pre_decml, &st->scale_post_decml);
@@ -364,7 +372,7 @@ static int als_parse_report(struct platform_device *pdev,
 /* Function to initialize the processing for usage id */
 static int hid_als_probe(struct platform_device *pdev)
 {
-	int ret = 0;
+	int ret = 0, max_channels;
 	static const char *name = "als";
 	struct iio_dev *indio_dev;
 	struct als_state *als_state;
@@ -398,15 +406,15 @@ static int hid_als_probe(struct platform_device *pdev)
 
 	ret = als_parse_report(pdev, hsdev,
 			       (struct iio_chan_spec *)indio_dev->channels,
-			       hsdev->usage,
-			       als_state);
+			       hsdev->usage, als_state, &max_channels);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to setup attributes\n");
 		return ret;
 	}
 
-	indio_dev->num_channels =
-				ARRAY_SIZE(als_channels);
+	/* +1 to include time stamp */
+	indio_dev->num_channels = max_channels + 1;
+
 	indio_dev->info = &als_info;
 	indio_dev->name = name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
-- 
2.25.1