linux-kernel - Re: [PATCH v2 2/3] hwrng: starfive - Add TRNG driver for StarFive SoC

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Message-ID: <Y7uEGxl8xJ1xxkKZ@gondor.apana.org.au>
Date:   Mon, 9 Jan 2023 11:03:55 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     JiaJie Ho <jiajie.ho@...rfivetech.com>
Cc:     Olivia Mackall <olivia@...enic.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Emil Renner Berthing <kernel@...il.dk>,
        Conor Dooley <conor.dooley@...rochip.com>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>
Subject: Re: [PATCH v2 2/3] hwrng: starfive - Add TRNG driver for StarFive SoC

On Mon, Jan 09, 2023 at 02:58:14AM +0000, JiaJie Ho wrote:
>
> My trng device requires sending a generate new number cmd before each read.
> It then only populates the data registers with new random number and raise an interrupt when ready.
> If user choose to not wait, they will always get stale bits. 
> Is it okay to always return error if wait=false ?

What is the length of the wait time? Is there an upper bound?
What is the average wait time?

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt