Hi, We are working with SMO8840 sensors integrated into several Acer all-in-one consumer PCs and we would like to make the accelerometer work with iio-sensor-proxy so that the display is auto-rotated based on the physical orientation of the device. One option is to inspect each device and then apply a mount matrix override in systemd, but we are looking for a generic solution. On Windows 10 the same functionality "just works" with the standard drivers from ST. Looking at the Windows 10 situation, I can see that the ACPI DSDT includes orientation data for the accelerometer device, in a package named _ONT. Using an in-memory DSDT override I was able to remove this package in order to examine the "raw" uncorrected data from Windows. I could then deduce the meanings of the 6 values in _ONT: the first 3 are axis ordering, so the values "1 0 2" imply that the data arrives in order of axis Y, X, Z, or in other words X and Y are swapped. The final 3 values are inversion flags, values "0 0 1" mean that the Z values must have their sign flipped. On this product the values are as above, 1 0 2 0 0 1 (swap X and Y, negate Z). acpidump: https://gist.github.com/dsd/588762aaa3b5601ff7fc6a8692755877 However, looking to implement the same _ONT logic on Linux, I was met with the surprise that the values read by st-accel-i2c do not match the Windows values taken even when _ONT is removed. This is a "landscape-first" device like the one illustrated here: https://blogs.windows.com/buildingapps/2015/09/03/new-sensor-features-in-windows-10/ Here is the data. I took Windows measurements using the "Sensors" app in the app store, and Linux measurements from sysfs in_accel_[xyz]_raw and manually normalized into the range -1 to +1. 1. Placed flat on the desk, face up "looking up at the sky" Windows (with _ONT): (0, 0, -1) Windows (no _ONT): (0, 0, 1) Linux: (0, 0, -1) 2. Normal landscape orientation (i.e. picture the device positioned the right way up and stuck to the wall) Windows (with _ONT): (0, -1, 0) Windows (no _ONT): (-1, 0, 0) Linux: (0, 1, 0) 3. Rotated 90 degrees right from normal landscape orientation Windows (with _ONT): (1, 0, 0) Windows (no _ONT): (0, 1, 0) Linux: (1, 0, 0) 4. Rotated 90 degrees left from normal landscape orientation Windows (with _ONT): (-1, 0, 0) Windows (no _ONT): (0, -1, 0) Linux: (-1, 0, 0) 5. Rotated 180 degrees from normal landscape orientation (i.e. upside down) Windows (with _ONT): (0, 1, 0) Windows (no _ONT): (1, 0, 0) Linux: (0, -1, 0) Why is the data read by Linux inconsistent with the data from Windows even after I remove the _ONT orientation adjustment? Thanks Daniel
