diff options
Diffstat (limited to 'drivers/iio/chemical/vz89x.c')
| -rw-r--r-- | drivers/iio/chemical/vz89x.c | 23 |
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, |