The ON_TIME delay of the power button is default set to 500ms. To improve the user experience, we would like to change that setting to 50ms. We use the devmem2 command to change the ON_TIME register setting in the SNVS_LP register. Unfortunately, it looks like the register gets reset to its default value when shutting down the board. This is how we can reproduce the issue:
- We are using the i.MX 8M Plus development board 8MPLUSLPD4-EVK
- We are running the LF_v5.15.52-2.1.0_images_IMX8MPEVK image
- Boot Linux and set the register: "devmem2 0x30370038 w 0x00100021"
- Reading back the register value to make sure it was set correctly.
- power off the board with the "poweroff" command
- Make sure the power cord is not removed
- Press the power button (short pressing does not start the board, we need to press at least 500ms)
- Hit a key to prevent autoboot in U-Boot
- Read back the register value in U-Boot with the command "md 0x30370038 1". The response is "00000021", which means the register got reset to its default value.
Even though the SNVS rails were not removed, the SNVS_LP register gets reset to its default value when shutting down the board. This means we are unable to reduce the minimum power button pressing time to 50ms. Is there anything we do wrong? How is it possible to reduce the delay between the button assertion and pmic_en_b signals is getting asserted?
