From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753144AbdDJKMM convert rfc822-to-8bit (ORCPT ); Mon, 10 Apr 2017 06:12:12 -0400 Received: from mailout4.samsung.com ([203.254.224.34]:48701 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751442AbdDJKMI (ORCPT ); Mon, 10 Apr 2017 06:12:08 -0400 X-AuditID: b6c32a2e-f79506d0000046c0-dd-58eb5a76f03a From: Bartlomiej Zolnierkiewicz To: Krzysztof Kozlowski Cc: James Hogan , Matt Mackall , Herbert Xu , Kukjin Kim , Javier Martinez Canillas , "David S. Miller" , Dave Airlie , David Airlie , Bernie Thompson , Greg Kroah-Hartman , PrasannaKumar Muralidharan , linux-kernel@vger.kernel.org, linux-metag@vger.kernel.org, linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, Stephan =?ISO-8859-1?Q?M=FCller?= Subject: Re: [PATCH v4 2/2] crypto: hw_random - Add new Exynos RNG driver Date: Mon, 10 Apr 2017 12:12:03 +0200 Message-id: <1713505.1UrJUbMZVN@amdc3058> User-Agent: KMail/4.13.3 (Linux/3.13.0-96-generic; KDE/4.13.3; x86_64; ; ) In-reply-to: <20170408133245.30147-3-krzk@kernel.org> MIME-version: 1.0 Content-transfer-encoding: 8BIT Content-type: text/plain; charset=iso-8859-1 X-Brightmail-Tracker: H4sIAAAAAAAAA02SWUwTURSGvTPT6dA4OpaCJ6JiGjVSI2oUva7RROO4RE2MCfqig0wApUA6 gOCLTaAioIALASsoRlBBDKYiCmpFCBSCaSGiRtDWaCUssqiA+0KZmvD25Zz//Pf8J5ch1UZ6 BhMVEy8aYoRoLa2iquqDdIsS9/eFLrGYGHza3kzg5x1FBG5zjVK4wJFK4faRQRqnXK2gcWbv TDxwqZvEH/vLCZz9vo/EDsdtJba8f6HALud3AjdlDSnws5oCGnd1pFE432ElcFFVFsIl2TaE c1tuURs0/Of2doKvLH1F8NXmN0q+qnYef6r6KeItZek0f2/0rYJ/XFiu5F2ZNoK/U3ycr8we U33IzaD5Qetzms/quY34L5bZu6fuV60NF6OjEkXD4vUHVZF29xllXCGblJInGdE7VQbyYYBb Ds6ss0hmf2h1VtAeVnMlCNw1OAOpxjiNgNKc18r/A2ftdlpuFCBoru5XyBMjCFyWVR6mudVw Jq1s3FXDBcHL31/HNSQ3oIDiVD8P+3Jb4eKQXKe4edDcbSIzEMOwY/rO9BWesh+3DSqtaYSH fbgQsA03jVuy3DT4ds5JyZYLwT3Q6rUPhnZjE+XZDbhWBn50DSk9nsDNAkstKe+/CayvGhUy +0KvrdKbKwB+l3R4D5GH4N5PkH3uICh7kOMVrYF6W5v3sSlw+qebkP1ZOHlCLUt4eFKYTsi8 EX6kNijkW435GG/mEzko0Dwhg3lCBvOEDEWILEP+YpykjxClkLhlwZKglxJiIoIPxeotaPxf 6oLvoz9F2+sQxyDtZPZbUm+oWiEkSsn6OgQMqdWw7N6+UDUbLiQfEw2xBwwJ0aJUhwIYSjud XVD6IlTNRQjx4hFRjBMN/7sE4zPDiDa7evzdZsF6+JhmddKCgCvpnUF181sI/a7mzM49hqN+ Ye6ViUcLL9xtjRp2DneXh815aN9RvC3BdBVU2r9Kk79w4Y+BqGnY0qY2frnY6FvcdD7w17Lt XQffZO6cGz+p/1rFI5N0ODbSUZJ6ZN/n2eKNFD1Zcd0c9UnH69YZNZeTtZQUKSzVkQZJ+AfJ LSHNkwMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrKKsWRmVeSWpSXmKPExsVy+t9jQd3SqNcRBmteq1v0njvJZHH11gIm i4v3v7FYzDnfwmJx5et7NovmxevZLLpfyVi8m/eC2eLN2zVMFv2PXzNbnD+/gd1i0+NrrBb3 7/1ksjjR94HV4vKuOWwWz261s1jMOL+PyWLBtj5Gi6X9xxktpp5ey+Ig4vHpyhUmjy0rbzJ5 7Jx1l91j2wFVj56dZxg9Nq3qZPPY/u0Bq8f+uWvYPe53H2fy2Lyk3mNLP1DV06ldbB7v911l 8+h7uYHR4/MmuQD+KDebjNTElNQihdS85PyUzLx0W6XQEDddCyWFvMTcVFulCF3fkCAlhbLE nFIgz8gADTg4B7gHK+nbJbhlnHsykb1gLm9F8/TiBsZHXF2MnBwSAiYSk86dY4OwxSQu3FsP ZHNxCAnMYpSYuXwSO4TzlVHi8uOZzCBVbAJWEhPbVzGC2CICmhLX/35nBSliFvjAKvFm9yom kISwgKfE7A8gCU4OFgFViZMvWoGaOTh4gRpud5qBhEUFvCS27GsHK+cUMJU4/uUEI8SyzYwS 69fvBTuJV0BQ4sfkeywgNrOAtsSTdxdYIWwdid7v35gnMALdiVA2C0nZLCRlCxiZVzFKpBYk FxQnpeca5aWW6xUn5haX5qXrJefnbmIEJ5Fn0jsYD+9yP8QowMGoxMMbUP0qQog1say4MvcQ owQHs5IIL2/o6wgh3pTEyqrUovz4otKc1OJDjKZAD05klhJNzgcmuLySeEMTcxNzYwMLc0tL EyMlcd7G2c/ChQTSE0tSs1NTC1KLYPqYODilGhiX939YcEOr4OiH2gz5Q3f3/8yqEXwZy77D mHvt/W1ngs0z53ifFZGz2vmCd9uV5yt4hdJPCF/epmCyNnCR98opSmt2hkycErdm185uoyyF R99Wzrryq4pl3qKGV/u5Vj198aHyirmVjMfFfzMTfqcpfNkZd3cxj0FUxT/tL5lrdb/mfhU7 Z/T2ixJLcUaioRZzUXEiANoyq+Y4AwAA X-MTR: 20000000000000000@CPGS X-CMS-MailID: 20170410101205epcas5p30c456307aaf8cdfeafd64fc77c92f1b4 X-Msg-Generator: CA X-Sender-IP: 203.254.230.27 X-Local-Sender: =?UTF-8?B?QmFydGxvbWllaiBab2xuaWVya2lld2ljehtTUlBPTC1LZXJu?= =?UTF-8?B?ZWwgKFRQKRvsgrzshLHsoITsnpAbU2VuaW9yIFNvZnR3YXJlIEVuZ2luZWVy?= X-Global-Sender: =?UTF-8?B?QmFydGxvbWllaiBab2xuaWVya2lld2ljehtTUlBPTC1LZXJu?= =?UTF-8?B?ZWwgKFRQKRtTYW1zdW5nIEVsZWN0cm9uaWNzG1NlbmlvciBTb2Z0d2FyZSBF?= =?UTF-8?B?bmdpbmVlcg==?= X-Sender-Code: =?UTF-8?B?QzEwG0VIURtDMTBDRDAyQ0QwMjczOTI=?= CMS-TYPE: 105P X-HopCount: 7 X-CMS-RootMailID: 20170408133346epcas2p1d015a5a590955524e98cfd1119414e21 X-RootMTR: 20170408133346epcas2p1d015a5a590955524e98cfd1119414e21 References: <20170408133245.30147-1-krzk@kernel.org> <20170408133245.30147-3-krzk@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Saturday, April 08, 2017 03:32:45 PM Krzysztof Kozlowski wrote: > Replace existing hw_ranndom/exynos-rng driver with a new, reworked one. > This is a driver for pseudo random number generator block which on > Exynos4 chipsets must be seeded with some value. On newer Exynos5420 > chipsets it might seed itself from true random number generator block > but this is not implemented yet. > > New driver is a complete rework to use the crypto ALGAPI instead of > hw_random API. Rationale for the change: > 1. hw_random interface is for true RNG devices. > 2. The old driver was seeding itself with jiffies which is not a > reliable source for randomness. > 3. Device generates five random 32-bit numbers in each pass but old > driver was returning only one 32-bit number thus its performance was > reduced. > > Compatibility with DeviceTree bindings is preserved. > > New driver does not use runtime power management but manually enables > and disables the clock when needed. This is preferred approach because > using runtime PM just to toggle clock is huge overhead. > > Another difference is reseeding itself with generated random data > periodically and during resuming from system suspend (previously driver > was re-seeding itself again with jiffies). > > Signed-off-by: Krzysztof Kozlowski > Reviewed-by: Stephan Müller > Reviewed-by: PrasannaKumar Muralidharan Reviewed-by: Bartlomiej Zolnierkiewicz Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics