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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 E3546C2D0A8 for ; Wed, 23 Sep 2020 08:01:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B1A2E235FD for ; Wed, 23 Sep 2020 08:01:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726151AbgIWIBQ (ORCPT ); Wed, 23 Sep 2020 04:01:16 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:50376 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726130AbgIWIBQ (ORCPT ); Wed, 23 Sep 2020 04:01:16 -0400 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4Bx9bq4QPjz9v09g; Wed, 23 Sep 2020 10:01:11 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id o-mWIuJAAecS; Wed, 23 Sep 2020 10:01:11 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4Bx9bq29Pnz9tx4Q; Wed, 23 Sep 2020 10:01:11 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id F1A5C8B7F4; Wed, 23 Sep 2020 10:01:11 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id yJFG8sUqnTVC; Wed, 23 Sep 2020 10:01:11 +0200 (CEST) Received: from [10.25.210.27] (unknown [10.25.210.27]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 8777A8B7F1; Wed, 23 Sep 2020 10:01:11 +0200 (CEST) Subject: Re: [PATCH] i2c: cpm: Fix i2c_ram structure To: Vincent Nicolas , "jochen@scram.de" Cc: "linuxppc-dev@lists.ozlabs.org" , "linux-i2c@vger.kernel.org" References: <20200922090400.6282-1-nicolas.vincent@vossloh.com> <956c4b63-f859-df0c-2836-80a988ee6aa9@csgroup.eu> From: Christophe Leroy Message-ID: <2ecfe18a-61f6-bb0e-22c5-b7ab79a77d03@csgroup.eu> Date: Wed, 23 Sep 2020 10:01:03 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org Le 23/09/2020 à 09:18, Vincent Nicolas a écrit : > > > > From: Christophe Leroy > Sent: Tuesday, 22 September 2020 14:38 > To: Vincent Nicolas ; jochen@scram.de > Cc: linuxppc-dev@lists.ozlabs.org ; linux-i2c@vger.kernel.org > Subject: Re: [PATCH] i2c: cpm: Fix i2c_ram structure > > > > Le 22/09/2020 à 11:04, nico.vince@gmail.com a écrit : >> From: Nicolas VINCENT >> >> the i2c_ram structure is missing the sdmatmp field mentionned in >> datasheet for MPC8272 at paragraph 36.5. With this field missing, the >> hardware would write past the allocated memory done through >> cpm_muram_alloc for the i2c_ram structure and land in memory allocated >> for the buffers descriptors corrupting the cbd_bufaddr field. Since this >> field is only set during setup(), the first i2c transaction would work >> and the following would send data read from an arbitrary memory >> location. >> >> Signed-off-by: Nicolas VINCENT >> --- >>    drivers/i2c/busses/i2c-cpm.c | 3 ++- >>    1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c >> index 1213e1932ccb..c5700addbf65 100644 >> --- a/drivers/i2c/busses/i2c-cpm.c >> +++ b/drivers/i2c/busses/i2c-cpm.c >> @@ -64,7 +64,8 @@ struct i2c_ram { >>         uint    txtmp;          /* Internal */ >>         char    res1[4];        /* Reserved */ >>         ushort  rpbase;         /* Relocation pointer */ >> -     char    res2[2];        /* Reserved */ >> +     char    res2[6];        /* Reserved */ >> +     uint    sdmatmp;        /* Internal */ > > On CPM1, I2C param RAM has size 0x30 (offset 0x1c80-0x1caf) > > Your change overlaps the miscellaneous area that contains CP Microcode > Revision Number, ref MPC885 Reference Manual §18.7.3 > > As far as I understand the mpc885 contains in the dts the compatible=fsl,cpm1-i2c which is used in cpm-i2c.c to either determine the address of the i2c_ram structure (cpm1), or dynamically allocate it with cpm_muram_alloc (cpm2). > In the first case the structure will indeed overlaps with the miscellaneous section but since the sdmatmp is only used by cpm2 hardware it shall not be an issue. > > Please, let me know if I am mistaken. If the patch cannot be accepted as is, I would gladly accept pointers on how to address this kind of issue. Please use a mail client that properly sets the > in front of original/answered text. Here your mailer has mixed you text and mine, that's unusable on the long term. I think you are right on the fact that it doesn't seem to be an issue. Nevertheless, that's confusing. What I would suggest is to leave res2[2] as is, and add something like: /* The following elements are only for CPM2 */ char res3[4]; /* Reserved */ uint sdmatmp; /* Internal */ Other solution (not sure that's the best solution thought) would be to do as in spi-fsl-cpm: use iic_t structure from asm/cpm1.h when CONFIG_CPM1 is selected and use iic_t from asm/cpm2.h when CONFIG_CPM2 is selected, taking into account that CONFIG_CPM1 and CONFIG_CPM2 are mutually exclusive at the time being. Christophe