From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Branden Subject: Re: [PATCH v2 2/2] hwrng: iproc-rng200 - Add Broadcom IPROC RNG driver Date: Mon, 2 Mar 2015 11:41:05 -0800 Message-ID: <54F4BCD1.2020401@broadcom.com> References: <1424888184-22180-3-git-send-email-sbranden@broadcom.com> <2093191.gujNGSl66k@wuerfel> <54F1E647.10106@broadcom.com> <2555599.AxGoQ20pkj@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <2555599.AxGoQ20pkj@wuerfel> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Arnd Bergmann Cc: bcm-kernel-feedback-list-dY08KVG/lbpWk0Htik3J/w@public.gmane.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Matt Mackall , Herbert Xu , Grant Likely , Ray Jui , Jonathan Richardson , Dmitry Torokhov , Anatol Pomazao , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org 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 > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html