Bug#793185: [linux-sunxi] Re: forwarding a bug: cpufreq missing in debian stable on a cuibeboard

[m.silentcreek@gmail.com]

Am Freitag, 24. Juli 2015 14:12:57 UTC+2 schrieb Thomas Kaiser:
> Maxime Ripard wrote:
>  > > What puzzles me is that exactly the same kernel (I used Igor Pečovnik's 
> 
> > > build system) provides working cpufreq support on 5 A20 devices and one it 
> 
> > > fails. 
> 
> > And none of those 5 use CPU voltage scaling.
> 
> Maybe I don't understand the whole meaning. But on a Banana Pi a few weeks ago [1] and on a pcDuino3 Nano I used the last days for USB/UAS benchmarks the cpufreq stuff was available below /sys/devices/system/cpu/cpu0/cpufreq/ and altering parameters always had an effect. But I will follow your advise, double check and report back.

I think what Maxime was trying to say is, that while all of your boards support Cpufreq, only the Cubietruck supports voltage scaling because only Cubietruck has the power regulator nodes defined in it's dts file (just have a look at the last lines of the Cubitruck dts file and compare that to the dts file, let's say, for Bananapi). On the other boards, the frequency is scaled, but the voltage always stays at 1.4V as set in U-Boot (that means the voltages in the cpufreq operating points are not used on these boards). At least that's what I understand after a recent email axchange with Chen-Yu Tsai. 

Cheers,

Timo