Hi,

Ondřej Jirman wrote:
>
> We have boards that have 1.1/1.3V switching, only 1.3V, fine tuned 
> voltage regulation and every such board will need it's own set of 
> operating points. 
>

Yes, and Allwinner's current BSP kernel code might encourage board makers 
to implement a forth variant: switching between 4 different voltages 
through GPIOs.

Currently we have 4 boards that rely on the simple '2 voltage regulation' 
all using 1.1V/1.3V: Orange Pi One and Lite and NanoPi M1 and NEO. Then 
there are 2 devices with (legacy) Linux support existing that use no 
voltage regulation at all: Banana Pi M2+ (according to schematic using 1.2V 
but in reality it's 1.3V VDD_CPUX) and Beelink X2. And according to Tsvetan 
if/when Olimex will release their 2 H3 boards we have two more with fixed 
but yet unknown VDD_CPUX voltage (since olimex fears overheating maybe they 
use 1.1V or 1.2V limiting max cpufreq to 816 or 1008 MHz). And all the 
bigger H3 based Orange Pi use the SY8106A voltage regulator being able to 
adjust VDD_CPUX in steps of 20mV allowing VDD_CPUX to exceed 1200 MHz (a 
reasonable value seems to be 1296 MHz since above throttling will be an 
issue without active cooling)

Things get even worse since Xunlong uses copper layers inside the PCB to 
spread the heat away from H3 so Orange Pi One/Lite do not overheat that 
much like eg. NanoPi M1 (and maybe NEO -- can tell next week when I get dev 
samples to play with). So while eg. Orange Pi One and NanoPi M1 switch 
between the same voltages in the same way we (Armbian) found that we have 
to allow M1 to downclock to even 240 MHz since when testing with legacy 
kernel really heavy workloads led to throttling that low (even CPU cores 
were killed at this low clockspeed -- same applies to BPi M2+ and Beelink 
X2)

So i would second Ondřej's suggestions since when we're talking about H3 
devices we're not talking about tablet SoCs with accompanied PMU but 3 
classes of devices behaving totally different in regard to cpufreq limits 
and dvfs OPPs (and maybe someone is already developing a new H3 device 
adding a forth variant switching between 4 different VDD_CPUX voltages)

Thomas

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