From: JiaJie Ho <jiajie.ho@starfivetech.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Olivia Mackall <olivia@selenic.com>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Emil Renner Berthing <kernel@esmil.dk>,
Conor Dooley <conor.dooley@microchip.com>,
"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>
Subject: RE: [PATCH v2 2/3] hwrng: starfive - Add TRNG driver for StarFive SoC
Date: Mon, 9 Jan 2023 03:41:14 +0000 [thread overview]
Message-ID: <e0c9944151b24e848af55221a4388301@EXMBX168.cuchost.com> (raw)
In-Reply-To: <Y7uEGxl8xJ1xxkKZ@gondor.apana.org.au>
> -----Original Message-----
> From: Herbert Xu <herbert@gondor.apana.org.au>
> Sent: 9 January, 2023 11:04 AM
> To: JiaJie Ho <jiajie.ho@starfivetech.com>
> Cc: Olivia Mackall <olivia@selenic.com>; Rob Herring <robh+dt@kernel.org>;
> Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>; Emil Renner
> Berthing <kernel@esmil.dk>; Conor Dooley <conor.dooley@microchip.com>;
> linux-crypto@vger.kernel.org; devicetree@vger.kernel.org; linux-
> kernel@vger.kernel.org; linux-riscv@lists.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?
>
The average wait time is around 20 microseconds.
I measured from writel cmd to wait_for_completion done.
Thanks
Jia Jie
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next prev parent reply other threads:[~2023-01-09 3:41 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-28 7:11 [PATCH v2 0/3] hwrng: starfive - Add driver for TRNG module Jia Jie Ho
2022-12-28 7:11 ` [PATCH v2 1/3] dt-bindings: rng: Add StarFive " Jia Jie Ho
2022-12-28 7:11 ` [PATCH v2 2/3] hwrng: starfive - Add TRNG driver for StarFive SoC Jia Jie Ho
2023-01-06 8:39 ` Herbert Xu
2023-01-08 14:13 ` JiaJie Ho
2023-01-09 2:58 ` JiaJie Ho
2023-01-09 3:03 ` Herbert Xu
2023-01-09 3:41 ` JiaJie Ho [this message]
2023-01-09 4:00 ` Herbert Xu
2023-01-09 4:33 ` JiaJie Ho
2022-12-28 7:11 ` [PATCH v2 3/3] riscv: dts: starfive: Add TRNG node for VisionFive 2 Jia Jie Ho
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