hi all,
this is a feature request, i logged an issue in the armbian forums
orange pi one overheats very hot after shutting down

https://forum.armbian.com/topic/8137-armbian-stretch-mainline-orange-pi-one-overheats-very-hot-after-shutting-down/


it turns out that after shutting down using shutdown -h now or poweroff or 
halt

the soc / cpu apparently remains running after the shutdown

i did that unaware of the situation and after some time i accidentally 
touch the board, the components are extremely hot possibly much higher than 
100 dec C including the cpu / soc. this is a possible fire hazard. 


when the os is running cpufreq utils cpu governer is running which keeps 
the temperature at 40-50 deg when idle, that is safe but after shutdown is 
done the opposite happens


apparently in the allwinner H3 soc, there is an or1k openrisc cpu (aka: 
arisc), apparently this or1k cpu can be used to perform various functions 
including shutting down the soc

http://linux-sunxi.org/AR100

https://github.com/megous/h3-firmware

https://megous.com/git/arisc-firmware/

https://github.com/Icenowy/h3-arisc-shutdown


in the 'legacy' 3.4 kernels for reasons that i do not know the system 
shutdown is apparently able to shutdown the soc core and the soc cools off 
after that

but in the 4.14 - 4.18 'mainline' kernels distributed with the armbian 
ubuntu boinc and debian stretch releases, this soc shutdown did not happen 
and the cpu runs very hot after the core is shutdown


i'm not really sure if the embedded arisc cpu mechanism is used for the 
shutdown. however, i'd like to make a request if this soc shutdown  
functionality could be added to the kernel? this is so that when systemd 
does a system shutdown the kernel eventually initiates shutdown of the soc 
and possibly peripherals


it is quite essential as users who are unaware of the problem may shutdown 
the board remotely thinking that it has shutdown and yet after that it 
becomes a fire hazard


currently i'm trying to use the above or1k resources / codes to attempt the 
shutdowns. however, i've not been able to find a safe place to patch in the 
systemd units or systemd scripts. those units or scripts when 
powerdown.target (and various others e.g. halt.target, shutdown.target) is 
run i observed that much of the processes are still running and various 
filesystems are still mounted when the units or scripts are run. hence it 
won't be safe to do so from a systemd unit or script as well


thanks much in advance


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