From: sbranden@broadcom•com (Scott Branden)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2 2/2] hwrng: iproc-rng200 - Add Broadcom IPROC RNG driver
Date: Sat, 28 Feb 2015 08:01:11 -0800 [thread overview]
Message-ID: <54F1E647.10106@broadcom.com> (raw)
In-Reply-To: <2093191.gujNGSl66k@wuerfel>
On 15-02-27 01:14 AM, Arnd Bergmann wrote:
> On Thursday 26 February 2015 14:26:02 Scott Branden wrote:
>> On 15-02-26 12:15 PM, Arnd Bergmann wrote:
>>>> On 15-02-25 11:17 AM, Arnd Bergmann wrote:
>>>>> On Wednesday 25 February 2015 10:16:24 Scott Branden wrote:
>>>> This code was following examples of other open source drivers - bcm2835
>>>> and exynos both use cpu_relax. I'll have to look into this more to
>>>> understand.
>>>>
>>>
>>> The majority of the driver apparently use udelay(10) to wait, which is
>>> not much better but at least consistent. The cpu_relax() call probably
>>> gives better throughput.
>>>
>>> I don't understand why none of the drivers actually attempts to
>>> msleep(), but that may be because the delay is much too long.
>>>
>>> Can you find out what the expected latency is for new data to
>>> become available on your hardware?
>> RNG generates at a nominal 1 Mbps. So to generate 32 bits of data takes
>> approximately 32 us.
>
> 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.
>
> Another option would be to use usleep_range() with the exact amount
> of time to wait for, the lower bound being the minimum number of
> bytes asked for and the fifo size, the upper bound being the fifo
> size.
>
> Arnd
>
next prev parent reply other threads:[~2015-02-28 16:01 UTC|newest]
Thread overview: 182+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Scott Branden <sbranden@broadcom.com>
2014-10-08 5:26 ` [PATCH V3 0/6] Add initial support for Broadcom Cygnus SoC Scott Branden
2014-10-08 5:27 ` [PATCH 1/6] ARM: cygnus: Initial " Scott Branden
2014-10-08 7:54 ` Arnd Bergmann
2014-10-08 12:27 ` Scott Branden
2014-10-08 13:28 ` Arnd Bergmann
2014-10-08 16:27 ` Scott Branden
2014-10-08 18:12 ` Arnd Bergmann
2014-10-08 18:45 ` Scott Branden
2014-10-08 22:16 ` Scott Branden
2014-10-09 7:32 ` Arnd Bergmann
2014-10-08 8:11 ` Russell King - ARM Linux
2014-10-08 11:17 ` Scott Branden
2014-10-08 11:41 ` Russell King - ARM Linux
2014-10-08 13:10 ` Rob Herring
2014-10-08 16:34 ` Scott Branden
2014-10-08 5:27 ` [PATCH 2/6] clk: Clock driver " Scott Branden
2014-10-08 5:27 ` [PATCH 3/6] dt-bindings: Document Broadcom Cygnus SoC and clock driver Scott Branden
2014-10-08 7:57 ` Arnd Bergmann
2014-10-08 10:58 ` Scott Branden
2014-10-08 13:35 ` Arnd Bergmann
2014-10-08 5:27 ` [PATCH 4/6] ARM: cygnus defconfig : Initial defconfig for Broadcom Cygnus SoC Scott Branden
2014-10-08 7:58 ` Arnd Bergmann
2014-10-08 11:01 ` Scott Branden
2014-10-08 5:27 ` [PATCH 5/6] ARM: dts: Enable " Scott Branden
2014-10-08 5:27 ` [PATCH 6/6] MAINTAINERS: Entry for Cygnus/iproc arm architecture and clock drivers Scott Branden
2014-10-09 22:44 ` [PATCH V4 0/7] Add initial support for Broadcom Cygnus SoC Scott Branden
2014-10-09 22:44 ` [PATCH V4 1/7] ARM: cygnus: Initial " Scott Branden
2014-10-10 9:50 ` Arnd Bergmann
2014-10-10 19:08 ` Scott Branden
2014-10-09 22:44 ` [PATCH V4 2/7] clk: Clock driver " Scott Branden
2014-10-09 22:44 ` [PATCH V4 3/7] dt-bindings: Document Broadcom Cygnus SoC and clock driver Scott Branden
2014-10-09 22:44 ` [PATCH V4 4/7] ARM: cygnus defconfig : Initial defconfig for Broadcom Cygnus SoC Scott Branden
2014-10-09 22:44 ` [PATCH V4 5/7] ARM: dts: Enable " Scott Branden
2014-10-10 10:08 ` Arnd Bergmann
2014-10-10 19:11 ` Scott Branden
2014-10-09 22:44 ` [PATCH V4 6/7] MAINTAINERS: Entry for Cygnus/iproc arm architecture and clock drivers Scott Branden
2014-10-09 23:00 ` Joe Perches
2014-10-09 23:18 ` Scott Branden
2014-10-09 22:44 ` [PATCH V4 7/7] ARM: multi_v7_defconfig: Enable ARCH_BCM_CYGNUS config Scott Branden
2014-10-10 9:59 ` Arnd Bergmann
2014-10-10 19:12 ` Scott Branden
2014-10-15 2:58 ` [PATCH v5 0/6] Add initial support for Broadcom Cygnus SoC Scott Branden
2014-10-15 2:58 ` [PATCH v5 1/6] ARM: cygnus: Initial " Scott Branden
2014-10-20 19:55 ` Arnd Bergmann
2014-10-20 22:59 ` Scott Branden
2014-10-21 5:48 ` Arnd Bergmann
2014-10-22 0:11 ` Scott Branden
2014-10-22 8:22 ` Arnd Bergmann
2014-10-22 17:12 ` Scott Branden
2014-10-15 2:58 ` [PATCH v5 2/6] dt-bindings: Document Broadcom Cygnus SoC and clocks Scott Branden
2014-10-15 2:58 ` [PATCH v5 3/6] ARM: cygnus defconfig : Initial defconfig for Broadcom Cygnus SoC Scott Branden
2014-10-15 2:58 ` [PATCH v5 4/6] ARM: dts: Enable " Scott Branden
2014-10-15 2:58 ` [PATCH v5 5/6] MAINTAINERS: Entry for Cygnus/iproc arm architecture Scott Branden
2014-10-15 2:58 ` [PATCH v5 6/6] ARM: mach-bcm: Consolidate currently supported IPROC SoCs Scott Branden
2014-10-22 2:09 ` [PATCH v6 0/6] Add initial support for Broadcom Cygnus SoC Scott Branden
2014-10-22 2:09 ` [PATCH v6 1/6] ARM: cygnus: Initial " Scott Branden
2014-10-22 2:09 ` [PATCH v6 2/6] dt-bindings: Document Broadcom Cygnus SoC and clocks Scott Branden
2014-10-22 2:09 ` [PATCH v6 3/6] ARM: cygnus defconfig : Initial defconfig for Broadcom Cygnus SoC Scott Branden
2014-10-22 2:09 ` [PATCH v6 4/6] ARM: dts: Enable " Scott Branden
2014-10-22 2:09 ` [PATCH v6 5/6] MAINTAINERS: Entry for Cygnus/iproc arm architecture Scott Branden
2014-10-22 2:09 ` [PATCH v6 6/6] ARM: mach-bcm: Consolidate currently supported IPROC SoCs Scott Branden
2014-10-22 20:57 ` [PATCH v7 0/7] Add initial support for Broadcom Cygnus SoC Scott Branden
2014-10-22 20:57 ` [PATCH v7 1/7] ARM: cygnus: Initial " Scott Branden
2014-10-22 20:57 ` [PATCH v7 2/7] dt-bindings: Document Broadcom Cygnus SoC and clocks Scott Branden
2014-10-22 20:57 ` [PATCH v7 3/7] ARM: cygnus defconfig : Initial defconfig for Broadcom Cygnus SoC Scott Branden
2014-10-22 20:57 ` [PATCH v7 4/7] ARM: dts: Enable " Scott Branden
2014-10-28 16:10 ` Arnd Bergmann
2014-10-28 19:41 ` Scott Branden
2014-10-22 20:57 ` [PATCH v7 5/7] MAINTAINERS: Entry for Cygnus/iproc arm architecture Scott Branden
2014-10-22 20:57 ` [PATCH v7 6/7] ARM: mach-bcm: Consolidate currently supported IPROC SoCs Scott Branden
2014-10-22 20:57 ` [PATCH v7 7/7] ARM: mach-bcm: ARCH_BCM_MOBILE: remove one level of menu from Kconfig Scott Branden
2014-10-28 19:53 ` [PATCH v8 0/8] Add initial support for Broadcom Cygnus SoC Scott Branden
2014-10-28 19:53 ` [PATCH v8 1/8] ARM: cygnus: Initial " Scott Branden
2014-10-28 19:53 ` [PATCH v8 2/8] dt-bindings: Document Broadcom Cygnus SoC and clocks Scott Branden
2014-10-28 19:53 ` [PATCH v8 3/8] ARM: cygnus defconfig : Initial defconfig for Broadcom Cygnus SoC Scott Branden
2014-10-28 19:53 ` [PATCH v8 4/8] ARM: dts: Enable " Scott Branden
2014-11-09 0:22 ` Olof Johansson
2014-11-09 6:13 ` Scott Branden
2014-11-09 6:49 ` Olof Johansson
2014-11-09 17:23 ` Greg Kroah-Hartman
2014-11-09 20:38 ` Arnd Bergmann
2014-11-10 5:17 ` Scott Branden
2014-11-10 8:11 ` Arnd Bergmann
2014-11-10 18:28 ` Scott Branden
2014-10-28 19:53 ` [PATCH v8 5/8] MAINTAINERS: Entry for Cygnus/iproc arm architecture Scott Branden
2014-10-28 19:53 ` [PATCH v8 6/8] ARM: mach-bcm: Consolidate currently supported IPROC SoCs Scott Branden
2014-10-28 19:53 ` [PATCH v8 7/8] ARM: mach-bcm: ARCH_BCM_MOBILE: remove one level of menu from Kconfig Scott Branden
2014-10-28 19:53 ` [PATCH v8 8/8] ARM: multi_v7_defconfig: Enable Broadcom Cygnus Scott Branden
2014-10-28 20:01 ` Arnd Bergmann
2014-10-28 20:06 ` Scott Branden
2014-10-28 20:13 ` Arnd Bergmann
2014-10-28 23:15 ` [PATCH v9 0/8] Add initial support for Broadcom Cygnus SoC Scott Branden
2014-10-28 23:15 ` [PATCH v9 1/8] ARM: cygnus: Initial " Scott Branden
2014-10-28 23:15 ` [PATCH v9 2/8] dt-bindings: Document Broadcom Cygnus SoC and clocks Scott Branden
2014-11-20 1:05 ` Mike Turquette
2014-10-28 23:15 ` [PATCH v9 3/8] ARM: cygnus defconfig : Initial defconfig for Broadcom Cygnus SoC Scott Branden
2014-10-28 23:15 ` [PATCH v9 4/8] ARM: dts: Enable " Scott Branden
2014-11-10 10:50 ` Paul Bolle
2014-11-10 18:35 ` Olof Johansson
2014-11-10 19:23 ` Paul Bolle
2014-10-28 23:15 ` [PATCH v9 5/8] MAINTAINERS: Entry for Cygnus/iproc arm architecture Scott Branden
2014-10-28 23:15 ` [PATCH v9 6/8] ARM: mach-bcm: Consolidate currently supported IPROC SoCs Scott Branden
2014-10-28 23:15 ` [PATCH v9 7/8] ARM: mach-bcm: ARCH_BCM_MOBILE: remove one level of menu from Kconfig Scott Branden
2014-10-28 23:15 ` [PATCH v9 8/8] ARM: multi_v7_defconfig: Enable Broadcom Cygnus Scott Branden
2014-11-10 5:55 ` [PATCH 1/2] ARM: multi_v7_defconfig: remove one level of menu from Kconfig Scott Branden
2014-11-10 5:55 ` [PATCH 2/2] ARM: multi_v7_defconfig: Enable Broadcom Cygnus Scott Branden
2015-02-10 0:06 ` [PATCH 0/4] Add support for IPROC SDHCI controller Scott Branden
2015-02-10 0:06 ` [PATCH 1/4] mmc: sdhci: add quirk for ACMD23 broken Scott Branden
2015-02-10 0:06 ` [PATCH 2/4] mmc: sdhci: do not set AUTO_CMD12 for multi-block CMD53 Scott Branden
2015-02-10 0:06 ` [PATCH 3/4] mmc: sdhci-iproc: add IPROC SDHCI driver Scott Branden
2015-02-10 0:06 ` [PATCH 4/4] mmc: sdhci-iproc: add device tree bindings Scott Branden
2015-03-02 23:50 ` Florian Fainelli
2015-03-04 23:14 ` Scott Branden
2015-02-26 17:28 ` [PATCH 0/4] Add support for IPROC SDHCI controller Scott Branden
2015-02-10 0:07 ` [PATCH 0/2] Add support for Broadcom RNG200 Scott Branden
2015-02-10 0:07 ` [PATCH 1/2] hwrng: iproc-rng200 - Add Broadcom IPROC RNG driver Scott Branden
2015-02-10 0:27 ` Joe Perches
2015-02-14 16:36 ` Scott Branden
2015-02-14 17:02 ` Scott Branden
2015-02-10 0:07 ` [PATCH 2/2] hwrng: iproc-rng200 - Add device tree bindings Scott Branden
2015-02-10 0:07 ` [PATCH 0/2] Add support for Broadcom keypad controller Scott Branden
2015-02-10 0:07 ` [PATCH 1/2] Input: bcm-keypad: add device tree bindings Scott Branden
2015-02-10 0:51 ` Dmitry Torokhov
2015-02-14 16:49 ` Scott Branden
2015-02-16 5:17 ` Dmitry Torokhov
2015-02-23 17:49 ` Dmitry Torokhov
2015-02-26 16:13 ` Scott Branden
2015-02-10 0:07 ` [PATCH 2/2] Input: bcm-keypad: Add Broadcom keypad controller Scott Branden
2015-02-10 1:02 ` Dmitry Torokhov
2015-02-14 17:12 ` Scott Branden
2015-02-25 18:16 ` [PATCH v2 0/2] Add support for Broadcom RNG200 Scott Branden
2015-02-25 18:16 ` [PATCH v2 1/2] hwrng: iproc-rng200 - Add device tree bindings Scott Branden
2015-03-02 23:47 ` Florian Fainelli
2015-02-25 18:16 ` [PATCH v2 2/2] hwrng: iproc-rng200 - Add Broadcom IPROC RNG driver Scott Branden
2015-02-25 18:43 ` Dmitry Torokhov
2015-03-03 0:50 ` Scott Branden
2015-02-25 19:17 ` Arnd Bergmann
2015-02-26 19:37 ` Scott Branden
2015-02-26 20:15 ` Arnd Bergmann
2015-02-26 22:26 ` Scott Branden
2015-02-27 9:14 ` Arnd Bergmann
2015-02-28 16:01 ` Scott Branden [this message]
2015-02-28 19:31 ` Arnd Bergmann
2015-03-02 19:41 ` Scott Branden
2015-03-02 10:23 ` [PATCH v2 0/2] Add support for Broadcom RNG200 Herbert Xu
2015-02-26 16:08 ` [PATCH v2 0/2] Add support for Broadcom keypad controller Scott Branden
2015-02-26 16:08 ` [PATCH v2 1/2] Input: bcm-keypad: add device tree bindings Scott Branden
2015-02-27 23:39 ` Dmitry Torokhov
2015-02-28 15:41 ` Scott Branden
2015-02-26 16:08 ` [PATCH v2 2/2] Input: bcm-keypad: Add Broadcom keypad controller Scott Branden
2015-02-27 23:44 ` Dmitry Torokhov
2015-02-28 15:52 ` Scott Branden
2015-02-28 14:16 ` Paul Bolle
2015-02-28 15:36 ` Scott Branden
2015-02-28 16:03 ` [PATCH v3 0/2] Add support for " Scott Branden
2015-02-28 16:03 ` [PATCH v3 1/2] Input: bcm-keypad: add device tree bindings Scott Branden
2015-02-28 16:03 ` [PATCH v3 2/2] Input: bcm-keypad: Add Broadcom keypad controller Scott Branden
2015-02-28 16:35 ` [PATCH v4 0/2] Add support for " Scott Branden
2015-02-28 16:35 ` [PATCH v4 1/2] Input: bcm-keypad: add device tree bindings Scott Branden
2015-03-03 0:04 ` Dmitry Torokhov
2015-02-28 16:35 ` [PATCH v4 2/2] Input: bcm-keypad: Add Broadcom keypad controller Scott Branden
2015-02-28 22:10 ` Dmitry Torokhov
2015-02-28 22:15 ` Dmitry Torokhov
2015-03-02 19:37 ` Scott Branden
2015-03-02 20:23 ` Dmitry Torokhov
2015-03-02 21:59 ` Scott Branden
2015-03-02 19:38 ` Scott Branden
2015-03-04 20:42 ` [PATCH v3 0/2] Add support for Broadcom RNG200 Scott Branden
2015-03-04 20:42 ` [PATCH v3 1/2] hwrng: iproc-rng200 - Add device tree bindings Scott Branden
2015-03-04 20:42 ` [PATCH v3 2/2] hwrng: iproc-rng200 - Add Broadcom IPROC RNG driver Scott Branden
2015-03-06 11:53 ` [PATCH v3 0/2] Add support for Broadcom RNG200 Herbert Xu
2015-03-05 15:59 ` [PATCH RESEND 0/4] Add support for IPROC SDHCI controller Scott Branden
2015-03-05 15:59 ` [PATCH 1/4] mmc: sdhci: add quirk for ACMD23 broken Scott Branden
2015-03-05 15:59 ` [PATCH 2/4] mmc: sdhci: do not set AUTO_CMD12 for multi-block CMD53 Scott Branden
2015-03-05 15:59 ` [PATCH 3/4] mmc: sdhci-iproc: add IPROC SDHCI driver Scott Branden
2015-03-05 15:59 ` [PATCH 4/4] mmc: sdhci-iproc: add device tree bindings Scott Branden
2015-03-05 16:16 ` [PATCH RESEND 0/4] Add support for IPROC SDHCI controller Ulf Hansson
2015-03-05 19:57 ` Florian Fainelli
2015-03-16 18:19 ` [PATCH] ARM: amba: Increase number of IRQs Scott Branden
2015-03-16 21:08 ` Russell King - ARM Linux
2015-03-16 21:18 ` Scott Branden
2015-03-16 21:16 ` [PATCH v2 1/1] " Scott Branden
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