From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by yocto-www.yoctoproject.org (Postfix, from userid 118) id A50AEE008D3; Fri, 7 Nov 2014 06:59:19 -0800 (PST) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on yocto-www.yoctoproject.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham version=3.3.1 X-Spam-HAM-Report: * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] Received: from mail.ahsoftware.de (h1446028.stratoserver.net [85.214.92.142]) by yocto-www.yoctoproject.org (Postfix) with ESMTP id 32D1FE002A8 for ; Fri, 7 Nov 2014 06:59:08 -0800 (PST) Received: by mail.ahsoftware.de (Postfix, from userid 65534) id A5CFE2C9C3F2; Fri, 7 Nov 2014 15:59:07 +0100 (CET) Received: from eiche.ahsoftware (p4FC3685E.dip0.t-ipconnect.de [79.195.104.94]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.ahsoftware.de (Postfix) with ESMTPSA id E3F7B2C9C212 for ; Fri, 7 Nov 2014 15:59:06 +0100 (CET) Received: by eiche.ahsoftware (Postfix, from userid 65534) id 31C5A7F846; Fri, 7 Nov 2014 15:59:06 +0100 (CET) Received: from krabat.ahsoftware (unknown [IPv6:feee::5246:5dff:fe8b:95f8]) by eiche.ahsoftware (Postfix) with ESMTP id 5D0358E4EE; Fri, 7 Nov 2014 14:55:29 +0000 (UTC) Message-ID: <545CDD60.9020901@ahsoftware.de> Date: Fri, 07 Nov 2014 15:55:28 +0100 From: Alexander Holler User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 MIME-Version: 1.0 To: Jon Nettleton , =?UTF-8?B?RXJpYyBCw6luYXJk?= References: <1415353415-3805-1-git-send-email-holler@ahsoftware.de> <20141107150003.27c16356@e6520eb.localdomain> In-Reply-To: Cc: meta-freescale@yoctoproject.org, Otavio Salvador Subject: Re: [PATCH 0/1] arm: imx: fsl_otp: make fuses (OTP memory) read-only X-BeenThere: meta-freescale@yoctoproject.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Usage and development list for the meta-fsl-* layers List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 07 Nov 2014 14:59:19 -0000 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Am 07.11.2014 15:31, schrieb Jon Nettleton: > Fair enough. Can we all agree that it should default to disabled? Anyone who is in need to write the OTP should be able to apply a patch=20 or to do a git revert in order to use that functionality. Those which are unable to do so, might not have an idea about OTP at=20 all, or they might not be aware how dangerous it is to write it (besides = the necessary knowledge about what to change). Regards, Alexander Holler > > -Jon > > On Fri, Nov 7, 2014 at 3:00 PM, Eric B=C3=A9nard wrot= e: >> Hi Alexander, >> >> Le Fri, 7 Nov 2014 10:43:34 +0100, >> Alexander Holler a =C3=A9crit : >>> Jon Nettleton made me aware that there is a driver which makes it ver= y >>> easy to write to the OTP from userspace. >>> >>> And I have to admit that I was mildly shocked. >>> >>> Because OTP stands for One Time Programmable, it means the write >>> functionality of that driver can be used only once per HW and if that= >>> is done wrong, the HW might be one of those famous electronic bricks >>> afterwards. >>> >>> So I've quickly written a patch which makes this driver to a friendly= >>> citizen instead of an heavily armed cowboy. >>> >>> I really, really think this patch should be attached to all trees whi= ch >>> are including fsl_otp.c. It applies without any error to >>> imx_3.10.17_1.0.1_ga, imx_3.10.31_1.1.0_beta, linux-linaro-lsk-v3.14-= mx6 >>> and likely any other tree which includes that driver. >>> >> That's not shocking to have this feature in a reference design's BSP := >> Freescale provides base source code to evaluate their SOC and writing >> OTP is one feature of their SOC. >> Then that's the end product designer's responsibility to enable/disabl= e >> features he wants or not on its product. >> >> The solution proposed by Otavio to add an option to ease the >> disabling of this feature is far better than fully removing the code. >> >> Best regards, >> Eric