How to bypass power button?

I have an M2 Berry, which has the power and reset buttons. I would like to configure it such that it turns on as soon as it receives power, without requiring pressing the power button, similar to Raspberry Pi boot behaviour. I have read that older BPI’s required soldering to achieve this, but could not find anything for the M2U / Berry. How can this be done?

Isn’t that default behaviour, at least with (Armbian) Linux? Dunno about Android.

Thank you for your response! I am running the latest Armbian (8 May 2023 build). Sometimes it indeed turns on immediately, but in other cases it doesn’t. For example, when issuing “sudo reboot” from the command line, it it will shut down and won’t boot until the power button is pressed, while I would expect it to just reboot. Is this expected behaviour? I can’t find documentation on what the power and reset buttons do exactly.

That is different problem and is related to power management support. Or lack of it. Those functions are coming (if) last to the mainline and for this particular board I am not sure this is covered or not. Documentation? You will need to obtain SoC and PMU chip (axp in this case) documentation & schematics. Which is not end user level document and supplied by Allwinner. If.

I see, thank you! So is there something like an LTS version that supports this? I don’t necessarily need to be on the bleeding edge, I just want maximum board compatibility, doesn’t even need to be Armbian. Which distributions are best for this?

I wouldn’t call legacy kernel LTS because there is little support to no support, no updates or fixes. Its an old kernel where HW support was developed by chip vendor (Allwinner in this case), but every other aspects are not very well. Terrible in some cases. No, you don’t want to have any experiences with Allwinner factory kernel … This kernel is here that you can’t argue with HW vendor about lack of function support. They (mainly) work, but kernel is static fork and has many limitations.

In case you have no interest to invest something into software support, adjust / lower your expectations. Remember, its open source.


Very clear, thank you again! One more question: I am experiencing random shutdowns (often under load) and have already replaced the power supply and cable, so I think it must be temperatures. However, I can’t get a readout of the temperature: armbianmonitor -m does not show temperatures for me, and the lm-sensors package (sudo sensors-detect) says that no sensors are found (but perhaps it doesn’t support ARM / Allwinner). The only value I’ve seen is the storage temperature in the welcome message, but I can’t find that in the system either. How do I get these readouts?

sensors-detect understand well known standard sensors from Intel / AMD / Nvidia world attached in some standard way (i2c/usb)

Reason why armbianmonitor doesn’t work is lack of readings from this SoC. Something must be missing / wrong on the kernel driver or its parameters. Study this:[email protected]/T/

Thanks again! I would like to give the patch a try, but how can I install it? Shouldn’t it already be in the Armbian 23.5 Bookworm (has kernel 6.2.16) that I’m currently running?

I am sorry, but i can’t possibly afford to guide you from that far and/or resolve your problem. If you don’t understand hints, find someone that can. No offence.

FYI. Project that is maintaining software you are paying nothing for and competitors steals from, needs on average 450 days to resolve one such issue.