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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10D68C433EF for ; Wed, 6 Oct 2021 18:12:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DEE206109F for ; Wed, 6 Oct 2021 18:12:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232137AbhJFSN6 (ORCPT ); Wed, 6 Oct 2021 14:13:58 -0400 Received: from esa1.mentor.iphmx.com ([68.232.129.153]:45087 "EHLO esa1.mentor.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232060AbhJFSN5 (ORCPT ); Wed, 6 Oct 2021 14:13:57 -0400 IronPort-SDR: OSp/viys+sJE0Omf6cdzmsxDTqOET/ylT8lgLh20G9u+TePfsymFCD5W9qYy3Z7jGM9n954GpR M2OnkUDiJbHnT7aMroXIUn5dnJz8vdNLhAuEmQlK+UWGz+Kcrml5c71cQwJF9znBABY3GLOqSW ugIDD/FGrHMI/Jim7pX0nZcW7KEPjVOVz7mY/kDoLwzU5uzl9tYfBpxDSH7yp+oO046s4/7AqP rxVgBk2sAlefTfx9WX1WfH9G43Rmk9vIR42mjyXF0ysdPWYofVqBqQs5RDPeHev5tJyR/Lxdx4 7rz/6vKnZE4DPQ4cVQHKRgMO X-IronPort-AV: E=Sophos;i="5.85,352,1624348800"; d="scan'208";a="69304206" Received: from orw-gwy-01-in.mentorg.com ([192.94.38.165]) by esa1.mentor.iphmx.com with ESMTP; 06 Oct 2021 10:12:05 -0800 IronPort-SDR: bOJ0//032ffDQdJa+MvKKqEi4kO/mOVjGeIG8kgg3dKoynHfGsQwH2rZLhm/44GcUfifRT+uPm B8H7ZDQebSKY48fad37Xc+m4B9bhpuu0s8/as9mfXymqQKv8haGx6QIOi21v98H/4q+sFOViN6 95TRxcUZZ082FqJB0MSuQvRa1JdOkifE+KVnwUqNj38HbqA3YkX4N3X8JWvc+qJc4Ugd7ANAOD qKfubhIKXkMJUAdEeUfhE1bFeHTbxhRaHCqDIVjSo6o7JkhnlpWdUnXLPJEvXWzmckvlnxe77e 0OY= From: Andrew Gabbasov To: 'Geert Uytterhoeven' CC: Linux-Renesas , Linux I2C , Linux Kernel Mailing List , Wolfram Sang , "Surachari, Bhuvanesh" References: <20210922160649.28449-1-andrew_gabbasov@mentor.com> In-Reply-To: Subject: RE: [PATCH] i2c: rcar: add SMBus block read support Date: Wed, 6 Oct 2021 21:11:51 +0300 Organization: Mentor Graphics Corporation Message-ID: <000001d7badd$a8512d30$f8f38790$@mentor.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQHXue1eCQdNXjaiK021FrevUeTu7qvGRbCQ Content-Language: en-us X-Originating-IP: [137.202.0.90] X-ClientProxiedBy: svr-ies-mbx-09.mgc.mentorg.com (139.181.222.9) To svr-ies-mbx-02.mgc.mentorg.com (139.181.222.2) Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org Hi Geert, Thank you for your review! > -----Original Message----- > From: Geert Uytterhoeven > Sent: Tuesday, October 05, 2021 4:32 PM > To: Gabbasov, Andrew > Cc: Linux-Renesas ; Linux I2C ; Linux Kernel > Mailing List ; Wolfram Sang ; Surachari, > Bhuvanesh > Subject: Re: [PATCH] i2c: rcar: add SMBus block read support > > Hi Andrew, > > On Wed, Sep 22, 2021 at 6:14 PM Andrew Gabbasov > wrote: > > The smbus block read is not currently supported for rcar i2c devices. > > This patchset adds the support to rcar i2c bus so that blocks of data > > can be read using SMbus block reads.(using i2c_smbus_read_block_data() > > function from the i2c-core-smbus.c). > > > > Inspired by commit 8e8782c71595 ("i2c: imx: add SMBus block read support") > > > > This patch (adapted) was tested with v4.14, but due to lack of real > > hardware with SMBus block read operations support, using "simulation", > > that is manual analysis of data, read from plain I2C devices with > > SMBus block read request. > > > > Signed-off-by: Bhuvanesh Surachari > > Signed-off-by: Andrew Gabbasov > > Thanks for your patch! > > > --- a/drivers/i2c/busses/i2c-rcar.c > > +++ b/drivers/i2c/busses/i2c-rcar.c > > @@ -429,9 +431,16 @@ static bool rcar_i2c_dma(struct rcar_i2c_priv *priv) > > /* > > * The last two bytes needs to be fetched using PIO in > > * order for the STOP phase to work. > > + * > > + * For SMBus block read the first byte was received using PIO. > > So it might be easier to read, and more maintainable, to keep the > old assignments: > > buf = priv->msg->buf; > len = priv->msg->len - 2; > > and adjust them for SMBus afterwards: > > if (block_data) { > /* For SMBus block read the first byte was received using PIO */ > buf++; > len--; > } > > ? > > > */ > > - buf = priv->msg->buf; > > - len = priv->msg->len - 2; > > + if (block_data) { > > + buf = priv->msg->buf + 1; > > + len = priv->msg->len - 3; > > + } else { > > + buf = priv->msg->buf; > > + len = priv->msg->len - 2; > > + } > > } else { > > /* > > * First byte in message was sent using PIO. > > And below we have another case handling buf and len :-( > > So perhaps: > > buf = priv->msg->buf; > len = priv->msg->len; > > if (read) { > /* > * The last two bytes needs to be fetched using PIO in > * order for the STOP phase to work. > */ > len -= 2; > } > if (!read || block_data) { > /* First byte in message was sent using PIO * > buf++; > len--; > } Probably I was trying to minimize the changes ;-) However, I agree with you that the whole code fragment can be simplified and your variant indeed looks more clean and understandable. Thank you for your suggestion, I'll submit version 2 of the patch with this fragment changed. Thanks! Best regards, Andrew