Note that I didn’t expect the values to change as they’re defined in the DTS, e.g.:
rockchip,pvtm-voltage-sel = <0x00 0x63b 0x00 0x63c 0x64f 0x01 0x650 0x668 0x02 0x669 0x68b 0x03 0x68c 0x6ae 0x04 0x6af 0x6cf 0x05 0x6d0 0x6f0 0x06 0x6f1 0x270f 0x07>;
I’m reading this as: 0-63b -> sel 0; 63c->64f -> sel 1 etc. So above for 1782 (0x6f6) it would match 6f1-270f hence 7.
I suspect that the opp-microvolt-L1…L7 values are voltages for various PVTM values for a given frequency, allowing to lower the voltage on some higher quality chips. This owuld mean that the last frequency to support an adjustable voltage is 2208 MHz, and above there are only fixed values. I haven’t yet found how they’re enabled, though the
opp-supported-hw value suspiciously looks like a bit mask of the PVTM values that will expose that frequency. With 0x80 for 2.4 GHz (pvtm-sel=7) you’re seeing your frequency, while I’m only seeing 2304 or 2352, and as there are holes in the mask this avoids some useless ones which almost overlap with the next one.
This would then allow to unlock high frequencies for lower grade chips by using a slight overvolting. Apparently at 2.208 the difference between L6 and L7 is 12.5mV and between L5 and L6 it’s 25mV. So it might be reasonable to try to compensate for silicon quality with a bit more heat.