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From: Rick Altherr <raltherr@google.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Alexander Clouter <alex@digriz.org.uk>,
	OpenBMC Maillist <openbmc@lists.ozlabs.org>,
	 Matt Mackall <mpm@selenic.com>,
	linux-crypto@vger.kernel.org,
	 Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1] hw_random: Fix timeriomem_rng for sub-jiffie update periods
Date: Wed, 5 Apr 2017 09:22:41 -0700	[thread overview]
Message-ID: <CAPLgG==p8W0vvWXMF7-9k_q482F7f9H1OJA_ZNbnV69tgYVZJw@mail.gmail.com> (raw)
In-Reply-To: <20170405125717.GB26558@gondor.apana.org.au>

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On Wed, Apr 5, 2017 at 5:57 AM, Herbert Xu <herbert@gondor.apana.org.au>
wrote:

> On Tue, Apr 04, 2017 at 02:43:07PM -0700, Rick Altherr wrote:
> > Some hardware RNGs provide a single register for obtaining random data.
> > Instead of signaling when new data is available, the reader must wait a
> > fixed amount of time between reads for new data to be generated.
> > timeriomem_rng implements this scheme with the period specified in
> > platform data or device tree.  While the period is specified in
> > microseconds, the implementation used a standard timer which has a
> > minimum delay of 1 jiffie and caused a significant bottleneck for
> > devices that can update at 1us.  By switching to an hrtimer, 1us periods
> > now only delay at most 2us per read.
> >
> > Migrated to new hw_random API while I in this driver.
> >
> > Signed-off-by: Rick Altherr <raltherr@google.com>
>
> Thanks Rick.  Could you split this into two patches? One doing
> the API conversion and the other one doing the substantive change
> to the entropy gathering?
>
> That way if there is a problem it'll be easier to track down.
>
>
Will do.


> 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
>

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      reply	other threads:[~2017-04-05 16:22 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-04 21:43 Rick Altherr
2017-04-05 12:57 ` Herbert Xu
2017-04-05 16:22   ` Rick Altherr [this message]

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