Hi Bruce, On Wed, Jun 2, 2021 at 11:14 AM Bruce Mitchell <bruce.mitchell@xxxxxxxxxxxxxxxxxx> wrote: > > Hello Guenter, > > I've been asked to expand the To list to include you and hwmon. > > In reference to: > https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-bus-iio > > There is this section: > > What: /sys/bus/iio/devices/iio:deviceX/in_pressureY_raw > What: /sys/bus/iio/devices/iio:deviceX/in_pressure_raw > KernelVersion: 3.8 > Contact: linux-iio@xxxxxxxxxxxxxxx > Description: > Raw pressure measurement from channel Y. Units after > application of scale and offset are kilopascal. > > What: /sys/bus/iio/devices/iio:deviceX/in_pressureY_input > What: /sys/bus/iio/devices/iio:deviceX/in_pressure_input > KernelVersion: 3.8 > Contact: linux-iio@xxxxxxxxxxxxxxx > Description: > Scaled pressure measurement from channel Y, in kilopascal. > > What: /sys/bus/iio/devices/iio:deviceX/in_humidityrelative_raw > KernelVersion: 3.14 > Contact: linux-iio@xxxxxxxxxxxxxxx > Description: > Raw humidity measurement of air. Units after application of > scale and offset are milli percent. > > What: /sys/bus/iio/devices/iio:deviceX/in_humidityrelative_input > KernelVersion: 3.14 > Contact: linux-iio@xxxxxxxxxxxxxxx > Description: > Scaled humidity measurement in milli percent. > > Nowhere do I find the unit kilopascal used in atmospheric pressure. > To stick with International System of Units and its Prefixes > https://en.wikipedia.org/wiki/International_System_of_Units#Prefixes > > The standard unit for used in atmospheric pressure measurements or > readings is the hectopascal (hPa), in meteorology, for atmospheric > pressure, the modern equivalent of the traditional millibar. > > What would it take to make this change to the standard for > https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-bus-iio ? > The short answer is "you don't". The ABI states that pressure is reported in kilopascal, not in hectopascal. We can't change the ABI because existing user space code depends on it. Changing it would be equivalent to changing the ABI for, say, temperature from degrees C to degrees F, or Kelvin. Quite frankly I don't see your problem. 1 kilopascal = 10 hectopascal. Take the reported number and multiply by 10. What am I missing ? Obviously I _am_ missing the entire discussion so far, so my response may be completely off track. If so, my apologies for the noise. Thanks, Guenter
