I know that POWER_BTN_N connects to GPIO on Xavier. It is handled by gpio-keys linux driver, and it is one of the WAKE signal to wake up from suspend/sleep. I also know how systemd-logind handles it to power off on button press, and how systemd-inhibit can disable logind’s handling so that other service e.g. GNOME GUI can handle it.
I have few questions regarding the hardware handling and EFM8SB10F8G:
- For auto-power-on case, is POWER_BTN_N signal useless in auto-power-on case? Or will the EFM8SB10F8G MCU simulate a button press by driving POWER_BTN_N low for short period?
- For button-power-on case, I know that POWER_BTN_N will representing the Power Button. But I am curious that how POWER_BTN_N is handled by Xavier side? Or is it only used internally by EFM8SB10F8G MCU? If it is used and handled by Xavier side, who and how it is handled? Most likely it is NOT handled by Linux because at that time Linux is not up and running yet. It is probably handled by software on BPMP or AON-SPE?
- On OEM document, it has power-off case where power button is press for >= 10s. Is this all handled by EFM8SB10F8G MCU where it will force a hardware shutdown by driving MODULE_POWER_ON low?