VIM2 big.LITTLE configuration


#1

Since the S912 big.LITTLE configuration is comprised of 2x Cortex-A53 processors, we are wondering if the LITTLE cluster can be adjusted to operate at its full clock speed (1.5 GHz rather than 1.0 GHz). We have no need for a low-voltage core based on our design requirements.

We’ve grepped the u-boot kvim2 source and found the LITTLE DVFS table. Assuming the clock is scaled in the kernel and not the hardware layer, we are wondering if simply adding 1200000000 and 1512000000 entries would allow the CPU to operate at its full clock speed? Aside from cooling, are there other things we should take into consideration?

If this is the only required change, does u-boot get recompiled each time the fenix script prepares the vim2 image?


#2

@numbqq please follow up.


#3

#4

Hi,

I’m also interested with this topic, any info from Khadas staff ?

thanks,


#5

by any chance, could adding extra entries to vlittle_dvfs_tbl there have any effect, or is it deemed to fail ?

(is this the correct u-boot branch for kvim2 anyway ?)


#6

Also interested in this - speeding up the smaller cores would be very useful. Any additional cooling requirements would be fine for my application