[PATCH] arm64: dts: rockchip: Describe why is HWRNG disabled in RK356x base dtsi

[Diederik de Haas]

Hi,

I'd have swapped 'is' and 'HWRNG' in the subject, but otherwise ...

On Mon Dec 2, 2024 at 3:44 PM CET, Dragan Simic wrote:
> 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@makrotopia.org/T/#u
> [2] https://lore.kernel.org/linux-rockchip/20241201234613.52322-1-pbrobinson@gmail.com/T/#u
>
> Signed-off-by: Dragan Simic <dsimic at manjaro.org>
> ---
>  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 at 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 at fe388000 {
>  		compatible = "rockchip,rk3568-rng";
>  		reg = <0x0 0xfe388000 0x0 0x4000>;

Reviewed-by: Diederik de Haas <didi.debian at cknow.org>

Thanks for this :-)
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