We are currently trying to use suspend mode in Linux but face a weird behaviour: When switching to suspend mode via
systemctl suspend, cutting off the supply voltage, waiting a little bit and restoring the power supply, the system won’t boot up again. This is only the case if the backup battery for the module’s RTC is connected to VCC_BAT. Even the reset button does not work anymore, as long as the battery is connected.
The suspend/wakup workflow in general is working, the RTC can be used to wakup the system as expected. We’re using a custom carrier board, but the behaviour can be reproduced using the eval board together with the official reference image, so we assume the problem to be on the SoM.
- Colibri iMX7D 1 GB V1.1A
- Col Evaluation V3.2B
Steps to Reproduce
- Flash reference Linux image to Colibri
- Populate CR2032 battery and make sure it is connected to VCC_BAT (Jumper JP23 set to INT)
- Connect to serial terminal via X27 and boot Linux
- log in and transition to suspend mode (
- Cut-off power supply and wait until buffer capacitors have discharged
- Reattach power supply and look at the serial terminal: Linux will not boot, SoM seems to be in an unknown state!
If you repeat the steps without the battery, everything works as expected, means that powercycling the eval board always causes a reset of the SoM.
Does anybody of you guys have similar issues? Any help on this would be really appreciated