Re: [PATCH v2 2/2] hwrng: iproc-rng200 - Add Broadcom IPROC RNG driver

[Arnd Bergmann]

On Wednesday 25 February 2015 10:16:24 Scott Branden wrote:
> This adds a driver for random number generator present on Broadcom
> IPROC devices.
> 
> Reviewed-by: Ray Jui <rjui@xxxxxxxxxxxx>
> Signed-off-by: Scott Branden <sbranden@xxxxxxxxxxxx>

The driver looks reasonable overall, I have just one question about
something that sticks out:

> +	while ((num_remaining > 0) && time_before(jiffies, idle_endtime)) {
...
> +
> +		/* Are there any random numbers available? */
> +		if ((ioread32(rng_base + RNG_FIFO_COUNT_OFFSET) &
> +				RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {
...
> +		} else {
> +			if (!wait)
> +				/* Cannot wait, return immediately */
> +				return max - num_remaining;
> +
> +			/* Can wait, give others chance to run */
> +			cpu_relax();
> +		}
> +	}
> +

It looks like you do a busy-loop around cpu_relax here if asked to wait.
Is this intentional? I would normally expect either cond_resched() or
some msleep() instead.

	Arnd
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