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-rw-r--r--drivers/iio/chemical/vz89x.c23
1 files changed, 21 insertions, 2 deletions
diff --git a/drivers/iio/chemical/vz89x.c b/drivers/iio/chemical/vz89x.c
index b45420039ca2..11e59a5a5112 100644
--- a/drivers/iio/chemical/vz89x.c
+++ b/drivers/iio/chemical/vz89x.c
@@ -85,6 +85,21 @@ static const struct attribute_group vz89x_attrs_group = {
.attrs = vz89x_attributes,
};
+/*
+ * Chipset sometime updates in the middle of a reading causing it to reset the
+ * data pointer, and causing invalid reading of previous data.
+ * We can check for this by reading MSB of the resistance reading that is
+ * always zero, and by also confirming the VOC_short isn't zero.
+ */
+
+static int vz89x_measurement_is_valid(struct vz89x_data *data)
+{
+ if (data->buffer[VZ89X_VOC_SHORT_IDX] == 0)
+ return 1;
+
+ return !!(data->buffer[VZ89X_REG_MEASUREMENT_SIZE - 1] > 0);
+}
+
static int vz89x_get_measurement(struct vz89x_data *data)
{
int ret;
@@ -106,6 +121,10 @@ static int vz89x_get_measurement(struct vz89x_data *data)
data->buffer[i] = ret;
}
+ ret = vz89x_measurement_is_valid(data);
+ if (ret)
+ return -EAGAIN;
+
data->last_update = jiffies;
return 0;
@@ -113,9 +132,9 @@ static int vz89x_get_measurement(struct vz89x_data *data)
static int vz89x_get_resistance_reading(struct vz89x_data *data)
{
- u8 *buf = &data->buffer[VZ89X_VOC_TVOC_IDX];
+ u8 *buf = &data->buffer[VZ89X_VOC_RESISTANCE_IDX];
- return buf[0] | (buf[1] << 8) | (buf[2] << 16);
+ return buf[0] | (buf[1] << 8);
}
static int vz89x_read_raw(struct iio_dev *indio_dev,