From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0869BC47094 for ; Mon, 7 Jun 2021 10:30:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC12F611BD for ; Mon, 7 Jun 2021 10:30:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230230AbhFGKcn (ORCPT ); Mon, 7 Jun 2021 06:32:43 -0400 Received: from fllv0015.ext.ti.com ([198.47.19.141]:60012 "EHLO fllv0015.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230097AbhFGKcm (ORCPT ); Mon, 7 Jun 2021 06:32:42 -0400 Received: from fllv0035.itg.ti.com ([10.64.41.0]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id 157AUbdc120986; Mon, 7 Jun 2021 05:30:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1623061837; bh=rs53RVoF/lk4i+SEk7UakVzfsG5HYB/uTZVfGqulVdY=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=S7vDk7mfNQQr3brRkEnboggqobywh872wwIcl/0Q2iKPP1P9soE3lqZYWqQSZcdLK 2Mt2RM57FnDYYIfIqjJ6szzhVMFv7XyQNsu9SWnvMs1a2WkKKM8kvxsVE9mJ675IrH qJ06islThJRpQVu8lzBASLqNSemEumL9RKLXs8NE= Received: from DLEE102.ent.ti.com (dlee102.ent.ti.com [157.170.170.32]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 157AUbVD101925 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 7 Jun 2021 05:30:37 -0500 Received: from DLEE102.ent.ti.com (157.170.170.32) by DLEE102.ent.ti.com (157.170.170.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Mon, 7 Jun 2021 05:30:37 -0500 Received: from lelv0327.itg.ti.com (10.180.67.183) by DLEE102.ent.ti.com (157.170.170.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2 via Frontend Transport; Mon, 7 Jun 2021 05:30:37 -0500 Received: from [10.250.234.148] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0327.itg.ti.com (8.15.2/8.15.2) with ESMTP id 157AUYdK093239; Mon, 7 Jun 2021 05:30:35 -0500 Subject: Re: [PATCH v5 3/5] mtd: spi-nor: otp: return -EROFS if region is read-only To: Michael Walle CC: , , , , , References: <20210604100252.9975-1-michael@walle.cc> <20210604100252.9975-4-michael@walle.cc> <1549db61-500a-e5df-9303-823b41457861@ti.com> <4ba7994b0cc8d436012a776ca14addca@walle.cc> <3e46bc75-6ace-f7c0-1b14-aae812554ac9@ti.com> <2559d150b3a0d964ece0c9e29e155ecc@walle.cc> From: Vignesh Raghavendra Message-ID: <4b3e1bde-09ff-eebd-8e93-8db7a5834f96@ti.com> Date: Mon, 7 Jun 2021 16:00:34 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <2559d150b3a0d964ece0c9e29e155ecc@walle.cc> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/7/21 3:26 PM, Michael Walle wrote: > Am 2021-06-07 08:47, schrieb Vignesh Raghavendra: >> On 6/7/21 11:38 AM, Michael Walle wrote: >>> Am 2021-06-07 07:46, schrieb Vignesh Raghavendra: >>>> On 6/4/21 6:45 PM, Michael Walle wrote: >>>>> Am 2021-06-04 15:07, schrieb Tudor.Ambarus@microchip.com: >>>>>> On 6/4/21 1:02 PM, Michael Walle wrote: >>>>>>> EXTERNAL EMAIL: Do not click links or open attachments unless you >>>>>>> know the content is safe >>>>>>> >>>>>>> SPI NOR flashes will just ignore program commands if the OTP >>>>>>> region is >>>>>>> locked. Thus, a user might not notice that the intended write >>>>>>> didn't end >>>>>>> up in the flash. Return -EROFS to the user in this case. From what >>>>>>> I can >>>>>>> tell, chips/cfi_cmdset_0001.c also return this error code. >>>>>>> >>>>>>> One could optimize spi_nor_mtd_otp_range_is_locked() to read the >>>>>>> status >>>>>>> register only once and not for every OTP region, but for that we >>>>>>> would >>>>>>> need some more invasive changes. Given that this is >>>>>>> one-time-programmable memory and the normal access mode is >>>>>>> reading, we >>>>>>> just live with the small overhead. >>>>>>> >>>>>>> Fixes: 069089acf88b ("mtd: spi-nor: add OTP support") >>>>>>> Signed-off-by: Michael Walle >>>>>>> Reviewed-by: Pratyush Yadav >>>>>>> --- >>>>>>>  drivers/mtd/spi-nor/otp.c | 36 ++++++++++++++++++++++++++++++++++++ >>>>>>>  1 file changed, 36 insertions(+) >>>>>>> >>>>>>> diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c >>>>>>> index 3898ed67ba1c..063f8fb68649 100644 >>>>>>> --- a/drivers/mtd/spi-nor/otp.c >>>>>>> +++ b/drivers/mtd/spi-nor/otp.c >>>>>>> @@ -249,6 +249,32 @@ static int spi_nor_mtd_otp_info(struct mtd_info >>>>>>> *mtd, size_t len, >>>>>>>         return ret; >>>>>>>  } >>>>>>> >>>>>>> +static int spi_nor_mtd_otp_range_is_locked(struct spi_nor *nor, >>>>>>> loff_t ofs, >>>>>>> +                                          size_t len) >>>>>>> +{ >>>>>>> +       const struct spi_nor_otp_ops *ops = nor->params->otp.ops; >>>>>>> +       unsigned int region; >>>>>>> +       int locked; >>>>>>> + >>>>>>> +       if (!len) >>>>>>> +               return 0; >>>>>>> + >>>>>> >>>>>> You won't need this if you put patch 4/5 before this one. With this: >>>>> >>>>> This patch will get backported to the stable kernels. Patch 4 on the >>>>> other hand does not. >>>>> >>>> >>>> I don't see why 4/5 cannot be marked for backport too as it makes 3/5 >>>> much cleaner? >>> >>> What kind of problem does 4/5 fix? I can't see how that patch would >>> apply to any rule in Documentation/process/stable-kernel-rules.rst. >>> >> >> Looking further, I don't see the need for 4/5 to be a separate patch. >> Patch 4/5 is simplifying spi_nor_mtd_otp_range_is_locked() by ensuring >> 'len' passed is never 0 which can be done in 3/5 when introducing >> spi_nor_mtd_otp_range_is_locked(). >> >> So why not squashed it into 3/5. > > Because, strictly speaking, it is not part of that particular fix > and IMHO violates "It must fix only one thing". But if you're fine > with that, I can squash the two. > > TBH I find it kinda funny to bend the rules, just to get rid of > these three lines of code or the ugliness that they will be removed > in the following patch. > This is still fixing only one thing "Indicating OTP writes are ignored when region is locked" (ie spi_nor_mtd_otp_range_is_locked() check). But, spi_nor_mtd_otp_range_is_locked() (as in 3/5) can be simplified if 'len != 0' is checked prior to calling the function. That's what 4/5 does which I believe can be squashed here. I just don't like code being refactored for the purpose of being able to be backported. It feels weird to have a piece of code being added in one commit, and then being deleted the very next commit. So strictly speaking 4/5 has to come before 3/5. But I am fine to live with this temporary ugliness if Tudor agrees. Regards Vignesh