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Date: Mon, 2 Mar 2015 11:41:05 -0800
From: Scott Branden <sbranden@broadcom.com>
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To: Arnd Bergmann <arnd@arndb.de>
CC: <bcm-kernel-feedback-list@broadcom.com>, Rob Herring <robh+dt@kernel.org>,
        Pawel Moll <pawel.moll@arm.com>, Mark Rutland <mark.rutland@arm.com>,
        "Ian Campbell" <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>, Matt Mackall <mpm@selenic.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Grant Likely <grant.likely@linaro.org>, Ray Jui <rjui@broadcom.com>,
        Jonathan Richardson <jonathar@broadcom.com>,
        Dmitry Torokhov <dtor@google.com>, Anatol Pomazao <anatol@google.com>,
        <devicetree@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>,
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Subject: Re: [PATCH v2 2/2] hwrng: iproc-rng200 - Add Broadcom IPROC RNG driver
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Hi Arnd,

Thanks for the suggested change.

On 15-02-28 11:31 AM, Arnd Bergmann wrote:
> On Saturday 28 February 2015 08:01:11 Scott Branden wrote:
>>> The udelay(10) that the other drivers have seems about appropriate then,
>>> and we can independently think of a way to refine the interface.
>>> Please add a comment that explains the rate. Also, is there some kind
>>> of FIFO present in the hwrng device? If it can store close to 1ms work
>>> of data (1000 bits), you can just use an msleep(1) to wait for the
>>> pool to recover.
>> FIFO is 512 bits.  I will look as to whether we can live with 1/2
>> throughput.
>
> In that case, I think usleep_range(min(len * 8, 500), 500)) would be
> a good compromise: it waits at most until the fifo is full, but might
> return earlier if enough bits are available to fulfill the request.
OK, will change in next version.
>
> 	Arnd
>