Voltage control does not work

[Decker]

Hey kids, it is me, again!

 

So, this time I found out (well, you maybe knew it before and I am dumbing around again) that voltage control does not work on Banana Pi (at least) mainline kernel. Well, if I am supposed to change it in linux-mainline/arch/arm/boot/dts/sun7i-a20.dtsi.

 

I tried to reach 1248000kHz, which is, of course, unstable. So I was adding and adding voltage, until I was too afraid to continue (1650000mV ). But BananaPi was unstable the same way (freez after few minutes of FTP transfer), no more (bad charger) or no less (would still need more voltage). So after few hours of re-compiling source and listening wonderful music I tried this: 1248000(kHz)@800000(mV), which is big overclock and 100000(mV) less than default voltage for lowest available frequency (144000kHz). But again, few minutes of FTP was possible. That should not be possible with 1248000(kHz)@800000(mV) [default max is 960000(kHz)@1400000(mV)]. I do not think that this would be able to boot to X.

 

Maybe I need to enable changing voltage somewhere, maybe it is not possible, I do not know. I only know that I am compiling/installing this the right way, because changed frequency in source file appears in scaling_available_freq later in running kernel.

 

I am sure that changing this voltage value does not have any effect.

 

Maybe I need to change some other value to enable voltage customization?

 

[tkaiser]

Please keep in mind that we're talking about cheap ARM SoCs and not x86 CPUs that ran through an extensive/expensive quality ensurance and selection process. What might work with your A20 (operating the beast at 2.0GHz with 0.1V) might break everywhere else. And vice versa.

[Decker]

You are definitely right about  extensive/expensive quality ensurance and selection process does not happen, but 2.0GHz@0.1V... man... that does not happen too...

If voltage control would work, there would be some value where board would not run. Not even blessed board can work without voltage... And I can set voltage to whatever I want, it is still the same.