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Date:   Tue, 10 Jan 2023 15:40:49 +0800
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     Jia Jie 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 v3 2/3] hwrng: starfive - Add TRNG driver for StarFive SoC
Message-ID: <Y70WgbySlio6cjew@gondor.apana.org.au>
References: <20230109165249.110279-1-jiajie.ho@starfivetech.com>
 <20230109165249.110279-3-jiajie.ho@starfivetech.com>
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In-Reply-To: <20230109165249.110279-3-jiajie.ho@starfivetech.com>
Precedence: bulk

On Tue, Jan 10, 2023 at 12:52:48AM +0800, Jia Jie Ho wrote:
>
> +static irqreturn_t starfive_trng_irq(int irq, void *priv)
> +{
> +	u32 status;
> +	struct starfive_trng *trng = (struct starfive_trng *)priv;
> +
> +	status = readl(trng->base + STARFIVE_ISTAT);
> +	if (status & STARFIVE_ISTAT_RAND_RDY) {
> +		writel(STARFIVE_ISTAT_RAND_RDY, trng->base + STARFIVE_ISTAT);
> +		complete(&trng->random_done);
> +	}
> +
> +	if (status & STARFIVE_ISTAT_SEED_DONE) {
> +		writel(STARFIVE_ISTAT_SEED_DONE, trng->base + STARFIVE_ISTAT);
> +		complete(&trng->reseed_done);
> +	}
> +
> +	if (status & STARFIVE_ISTAT_LFSR_LOCKUP) {
> +		writel(STARFIVE_ISTAT_LFSR_LOCKUP, trng->base + STARFIVE_ISTAT);
> +		/* SEU occurred, reseeding required*/
> +		writel(STARFIVE_CTRL_EXEC_RANDRESEED, trng->base + STARFIVE_CTRL);

This could occur at the same time as a GENE_RANDNUM write so perhaps
you should add some locking?

> +	ret = devm_request_irq(&pdev->dev, irq, starfive_trng_irq, 0, pdev->name,
> +			       (void *)trng);
> +	if (ret)
> +		return dev_err_probe(&pdev->dev, irq,
> +				     "Failed to register interrupt handler\n");

...

> +	init_completion(&trng->random_done);
> +	init_completion(&trng->reseed_done);

These completion initialisations should be moved above the IRQ
registration because you should always be prepared to get spurious
interrupts.

Otherwise the patch looks good.

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