Re: [PATCH 1/3] riscv: dts: spacemit: Add cpu scaling for Milk-V Jupiter

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] This problem wasn't introduced by this patch, but wiring it up to cpufreq makes it a serious hardware safety risk: the CPU supply regulator (`buck1_0v9`) has an overly permissive maximum voltage constraint of 3.45V, which could physically damage the CPU.
--

--- Patch [1]: [PATCH 1/3] riscv: dts: spacemit: Add cpu scaling for Milk-V Jupiter ---
commit 4e25fb96470d1ad37415e03a27de699ef1f0da26
Author: Aurelien Jarno <aurelien@aurel32.net>

riscv: dts: spacemit: Add cpu scaling for Milk-V Jupiter

This commit enables CPU DVFS on the Milk-V Jupiter board by including the OPP
tables and wiring the CPU nodes to the CPU regulator supply.

> diff --git a/arch/riscv/boot/dts/spacemit/k1-milkv-jupiter.dts b/arch/riscv/boot/dts/spacemit/k1-milkv-jupiter.dts
> index b61f5995ec771..3c16d0c20050e 100644
> --- a/arch/riscv/boot/dts/spacemit/k1-milkv-jupiter.dts
> +++ b/arch/riscv/boot/dts/spacemit/k1-milkv-jupiter.dts
[ ... ]
> @@ -107,6 +108,38 @@ &combo_phy {
>  	status = "okay";
>  };
>  
> +&cpu_0 {
> +	cpu-supply = <&buck1_0v9>;
> +};
[ ... ]
> @@ -209,7 +242,7 @@ pmic@41 {
>  		dldoin2-supply = <&buck5>;
>  
>  		regulators {
> -			buck1 {
> +			buck1_0v9: buck1 {
>  				regulator-min-microvolt = <500000>;
>  				regulator-max-microvolt = <3450000>;

[Severity: High]
This is a pre-existing issue, but by wiring up the CPU supply for cpufreq in 
this patch, does it introduce a severe hardware safety risk?

The buck1_0v9 regulator retains a very permissive maximum voltage constraint 
of 3.45V. Because the safe physical limit for the CPU is 1.05V (as defined in 
k1-opp.dtsi), could this permanently damage the hardware if a kernel bug, opp 
misconfiguration, or privileged userspace requests a higher voltage up to the 
board-defined maximum?

Should the board-level constraint be clamped to the safe physical limits of 
the CPU (e.g., 1050000 microvolts) to prevent the regulator from supplying a 
destructive voltage?

>  				regulator-ramp-delay = <5000>;
>  				regulator-always-on;
>  			};

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260728211020.1248676-1-aurelien@aurel32.net?part=1