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SubjectRe: [PATCH 2/2] hwrng: mtk: Add driver for hardware random generator on MT7623 SoC
Hi Sean,

Mostly looks good, have few minor comments.

On 13 April 2017 at 12:35, <sean.wang@mediatek.com> wrote:
> +static bool mtk_rng_wait_ready(struct hwrng *rng, bool wait)
> +{
> + struct mtk_rng *priv = to_mtk_rng(rng);
> + int ready;
> +
> + ready = readl(priv->base + RNG_CTRL) & RNG_READY;
> + if (!ready && wait)
> + readl_poll_timeout_atomic(priv->base + RNG_CTRL, ready,
> + ready & RNG_READY, USEC_POLL,
> + TIMEOUT_POLL);
> + return !!ready;
> +}

Use readl_poll_timeout_atomic's return value or -EIO instead of
!!ready. This will simplify mtk_rng_read.

> +static int mtk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
> +{
> + struct mtk_rng *priv = to_mtk_rng(rng);
> + int retval = 0;
> +
> + while (max >= sizeof(u32)) {
> + if (!mtk_rng_wait_ready(rng, wait))
> + break;
> +
> + *(u32 *)buf = readl(priv->base + RNG_DATA);
> + retval += sizeof(u32);
> + buf += sizeof(u32);
> + max -= sizeof(u32);
> + }
> +
> + if (unlikely(wait && max))
> + dev_warn(priv->dev, "timeout might be not properly set\n");

Is this really necessary? Better to choose proper timeout than
providing this warning message. In rare cases if the timeout could
occur due to some reason (may be a hardware fault) print appropriate
warning message.

> + return retval || !wait ? retval : -EIO;
> +}

Set retavl to mtk_rng_wait_ready and return retval.

Regards,
Prasanna

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