How do you overclock the VF2?

bucketoffun · June 1, 2023, 5:23pm

How do you overclock the VF2? I’m using one right now to type this message and it’s pretty slow. Heat shouldn’t be an issue as I can have a full load without a heatsink and stay downright chilly, and this one I’m using has a hulking heatsink with a fan. A similar topic How to get CPU frequency and how to overclock it? is filled with excuses for the original VF which got super hot even with a heatsink.

easytarget · June 1, 2023, 7:21pm

StarFive have said, essentially, that the JH7110 runs up to 1.8 Ghz, but they set it in their releases to 1.5 to ensure people don’t have thermal issues. I suspect that 1.8 would be stable with a good fan+heatsink.

I’m not sure how to overclock, I imagine it needs to start with a modified dtb file loaded at boot.

Kudos to the first person to hit 2 Ghz on this! Double kudos to anyone overclocking the GPU or PCIe bus…

easytarget · June 2, 2023, 1:38pm

Looking further we have:

github.com

starfive-tech/linux/blob/JH7110_VisionFive2_upstream/arch/riscv/boot/dts/starfive/jh7110.dtsi#L195


      
          					opp-microvolt = <800000>;
          			};
          			opp-500000000 {
          					opp-hz = /bits/ 64 <500000000>;
          					opp-microvolt = <800000>;
          			};
          			opp-750000000 {
          					opp-hz = /bits/ 64 <750000000>;
          					opp-microvolt = <800000>;
          			};
          			opp-1500000000 {
          					opp-hz = /bits/ 64 <1500000000>;
          					opp-microvolt = <1040000>;
          			};
          	};
          
          
	dvp_clk: dvp-clock {
          		compatible = "fixed-clock";
          		clock-output-names = "dvp_clk";
          		#clock-cells = <0>;
          	};

I’d start by adding a new entry to that, below the 1500000 (1.5Ghz) definition.

			opp-1800000000 {
					opp-hz = /bits/ 64 <1800000000>;
					opp-microvolt = <1040000>;
			};

The big issue is the opp-microvolt value, if you look at the frequency list you will see it stays at 800000 up to 750Mhz (0.8 volts, presumably), but goes up to 1040000 (1.04 volts) for the 1.5Ghz band.

I’d start by trying the same opp-microvolt setting for 1.8GHz as used for 1.5. But it /may/ need increasing… a lack of system stability will quickly tell you if it is an issue. I have no idea of this values stepping and/or limits for the JH7110 so digging into the datasheet and other sources is necessary! Don’t just casually mess with this value without understanding it first, if the cpu max is 1v then increasing it further could be disastrous.

Stat_headcrabed · June 3, 2023, 7:12pm

I heard from Icesnowy that 1.75Ghz mode would break USB/Eth due to clock changing for those IPs.

typedef · June 4, 2023, 8:42am

From JH7110 datasheet:
page 79:
| VDD09_CPU | VDD_CPU | 2 | 0.9 to 1.0 | CPU core power supply, which can be adjusted to 1.0 V |
page 86:
| VDD | Power supply for Core | 0.81 | 0.99 | V |
That’s min (0.81) and max (0.99).
Same page:
| VDD | VSS | Core power supply | 0.81 | 0.9 | 0.99 | V |
That’s min(0.81), typical (0.9) and max (0.99).
Someone from StarFive should know better but I wouldn’t put over 1V on it.
Also, this is for Core voltage, not I/O.

krory · September 18, 2023, 8:48pm

hi, how can i use this? i just compile the whole thing? (changing it)

sorry for the stupid question