vr@m

As I've said earlier, it 20mA per pin ! I've also said that if you sums up many pins, it is up to the quality of the PCB design if it could handle that, for your example 40 pins multiply 20mA, this means that the VCC would need to supply a total 800mA to the SoC, if VCC lines on PCB are not huge enough, this will produce a voltage drop on those lines and maybe the SoC will brownout and reset/crash.
 

This kind of buffer strength is pretty normal ...
If you need more, such 500mA per pin, you can add MOSFET or DARLINGTON, or chip like ULN2803, which is in fact an array of 8 darlingtons.

Thank you @martinayotte, I will try this image. You and Igor gave too good reasons to change to armbian.