Hi Zhang,
I double checked with hardware and software engineer that it is related with the software driver.
Here is the driver.
<LINK_TEXT text=“https://github.com/beagleboard/linux/bl … tiehrpwm.c”>https://github.com/beagleboard/linux/blob/4.19/drivers/pwm/pwm-tiehrpwm.c</LINK_TEXT>
I see you already posted the issue on the github. So please follow up with github. Thanks.
best rgds
Bill