Despite the presence of the hardware random number generator (HWRNG) in the different Rockchip RK356x SoC variants, it remains disabled for the RK3566 SoC because testing showed [1] that it produces unacceptably low quality of random data, for some yet unknown reason. The HWRNG is enabled for the RK3568 SoC, on which the testing showed good quality of the generated random data. To avoid possible confusion in the future, [2] let's have this described briefly in the RK356x base SoC dtsi. [1] https://lore.kernel.org/linux-rockchip/cover.1720969799.git.daniel@xxxxxxxxxxxxxx/T/#u [2] https://lore.kernel.org/linux-rockchip/20241201234613.52322-1-pbrobinson@xxxxxxxxx/T/#u Signed-off-by: Dragan Simic <dsimic@xxxxxxxxxxx> --- arch/arm64/boot/dts/rockchip/rk356x-base.dtsi | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm64/boot/dts/rockchip/rk356x-base.dtsi b/arch/arm64/boot/dts/rockchip/rk356x-base.dtsi index 62be06f3b863..ab8f42c0a843 100644 --- a/arch/arm64/boot/dts/rockchip/rk356x-base.dtsi +++ b/arch/arm64/boot/dts/rockchip/rk356x-base.dtsi @@ -1032,6 +1032,11 @@ sdhci: mmc@fe310000 { status = "disabled"; }; + /* + * Testing showed that the HWRNG found in RK3566 produces unacceptably + * low quality of random data, so the HWRNG isn't enabled for all RK356x + * SoC variants despite its presence. + */ rng: rng@fe388000 { compatible = "rockchip,rk3568-rng"; reg = <0x0 0xfe388000 0x0 0x4000>;
