On 7/31/21 9:39 AM, Jonathan Cameron wrote:
On Tue, 27 Jul 2021 18:35:19 +0200
Andreas Klinger <ak@xxxxxxxxxxxxx> wrote:
sgp40 is a gas sensor used for measuring the air quality.
This driver is reading the raw resistance value which can be passed to
a userspace algorithm for further calculation.
The raw value is also used to calculate an estimated absolute voc index
in the range from 0 to 500. For this purpose the raw_mean value of the
resistance for which the index value is 250 might be set up as a
calibration step.
Compensation of relative humidity and temperature is supported and can
be used by writing to device attributes of the driver.
There is a predecesor sensor type (sgp30) already existing. This driver
module was not extended because the new sensor is quite different in its
i2c telegrams.
Signed-off-by: Andreas Klinger <ak@xxxxxxxxxxxxx>
Hi Andreas,
Non standard ABI in here, so we are missing documentation in Documentation/ABI/testing/sysfs-bus-iio-*
Otherwise a few suggestions inline.
Thanks,
Jonathan
---
[ ... ]
+static int sgp40_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int *val,
+ int *val2, long mask)
+{
+ struct sgp40_data *data = iio_priv(indio_dev);
+ int ret;
+ u16 raw;
+ int voc;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ mutex_lock(&data->lock);
+ ret = sgp40_measure_raw(data, &raw);
+ if (ret) {
+ mutex_unlock(&data->lock);
+ return ret;
+ }
+ *val = raw;
+ ret = IIO_VAL_INT;
+ mutex_unlock(&data->lock);
+ break;
+ case IIO_CHAN_INFO_PROCESSED:
+ mutex_lock(&data->lock);
+ ret = sgp40_measure_raw(data, &raw);
+ if (ret) {
+ mutex_unlock(&data->lock);
+ return ret;
+ }
+ ret = sgp40_calc_voc(data, raw, &voc);
+ if (ret) {
+ mutex_unlock(&data->lock);
+ return ret;
+ }
+ *val = voc;
+ ret = IIO_VAL_INT;
+ mutex_unlock(&data->lock);
You are holding the lock longer than needed - it would be good
to reduce this, hopefully removing the need for unlocking separately
in each of the error paths.
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return ret;
Drop this as you can't get here.
Are you sure ? I see several "break;" above.
Guenter
