This should help in https://github.com/pwr/Solaar/issues/49. This information
was shared by Nestor Lopez Casado from Logitech.
What remains unclear are the 0x25 and 0x26 values for r1 (Charging state). It is
also not clear whether r0 (Battery/Charging level) always reports 0x00 while
charging the Performance MX. (Perhaps this is only reported the first few
seconds?)
Peter Wu