Fixes common MPU-9250 accelerometer issues for RPi Linux MCU and
improves reliability on all other architectures by adjusting the MPU-*
reading algorithm to only read whole Klipper messages' worth of
data from MPU-* and eliminating many unnecessary checks of the MPU FIFO
fill-level that consumed bus bandwidth needed for data transfer. Fixes
intermittent "Lost communication with MCU 'rpi'" due to "Timer too
close" and transposed / corrupted data due to FIFO overrun/data loss
when using MPU-* accelerometers. In addition FIFO overrun checks are
performed by testing the MPU interrupt flag vs. inferring from the FIFO
fill level.
Stress tested for 13hrs with two MPU-6500 attached to one I2C bus on RPi
and one on a PR2040
Stress tested for 23hrs with two MPU-6500 attached to one I2C bus on RPi
and one on a ATmega328P (Seeduino Nano)
Signed-off-by: Matthew Swabey <matthew@swabey.org>
80a7744b42