linux-kernel - Re: [PATCH v2 2/3] crypto: sun8i-ce - Add TRNG clock to the D1 variant

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Message-ID: <3212177.44csPzL39Z@jernej-laptop>
Date:   Thu, 05 Jan 2023 17:29:34 +0100
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     Corentin Labbe <clabbe.montjoie@...il.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>,
        Chen-Yu Tsai <wens@...e.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Samuel Holland <samuel@...lland.org>
Cc:     Samuel Holland <samuel@...lland.org>,
        Albert Ou <aou@...s.berkeley.edu>,
        Conor Dooley <conor@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-sunxi@...ts.linux.dev
Subject: Re: [PATCH v2 2/3] crypto: sun8i-ce - Add TRNG clock to the D1 variant

Dne sobota, 31. december 2022 ob 23:01:44 CET je Samuel Holland napisal(a):
> At least the D1 variant requires a separate clock for the TRNG.
> Without this clock enabled, reading from /dev/hwrng reports:
> 
>    sun8i-ce 3040000.crypto: DMA timeout for TRNG (tm=96) on flow 3
> 
> Experimentation shows that the necessary clock is the SoC's internal
> RC oscillator. This makes sense, as noise from the oscillator can be
> used as a source of entropy.
> 
> Signed-off-by: Samuel Holland <samuel@...lland.org>

Reviewed-by: Jernej Skrabec <jernej.skrabec@...il.com>

Best regards,
Jernej