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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1B63CC433EF for ; Tue, 19 Apr 2022 07:45:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:CC:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=aYbbgAATFFMQ3dHSQUrasSFFJRjK6RdNtY6yUaHpQnY=; b=cTxAmDuzf+JLDI LdUy7s2VLb971LlbaEikuHpRVImcTIFRJfSjxqnsAODaF3vol016VS4QFFCqnX6r1YoWIDbstg9ny G875x5GljDVDoPoNAmXJ/a9DQcEHu5aLzOUyfQGfj6YsrZXlHcpiMV5gdJllJHZeJbz9v39eUFor2 0oxTeT6BxYH1bKiDgKkwreUNc+wSRtuwX12hqZf7P0FazJtLUdIX2c9syoJdMPRYPm1ssQSmmSJu4 M+AD4GkvEQBJw7yimUvvusaHrONcil0yGA1Nv1m/Jpz1cyyuFWrah1f3CslZmdE0RILE+ENG217Cj 6yEwGSyB33qSSUS31X6Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ngiY1-0027Cz-VM; Tue, 19 Apr 2022 07:45:18 +0000 Received: from mail-sh.amlogic.com ([58.32.228.43]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ngiIl-001ztS-7c; Tue, 19 Apr 2022 07:29:37 +0000 Received: from [10.18.29.47] (10.18.29.47) by mail-sh.amlogic.com (10.18.11.5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.14; Tue, 19 Apr 2022 15:29:20 +0800 Message-ID: Date: Tue, 19 Apr 2022 15:29:19 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH V2 1/2] tty: serial: meson: Add a 12MHz internal clock rate to calculate baud rate in order to meet the baud rate requirements of special BT modules Content-Language: en-US To: Andy Shevchenko CC: "open list:SERIAL DRIVERS" , linux-arm Mailing List , linux-amlogic , Linux Kernel Mailing List , Greg Kroah-Hartman , Neil Armstrong , Kevin Hilman , Jerome Brunet , Jiri Slaby , Martin Blumenstingl References: <20220418053202.24528-1-yu.tu@amlogic.com> <20220418053202.24528-2-yu.tu@amlogic.com> From: Yu Tu In-Reply-To: X-Originating-IP: [10.18.29.47] X-ClientProxiedBy: mail-sh.amlogic.com (10.18.11.5) To mail-sh.amlogic.com (10.18.11.5) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220419_002931_352039_22A9E79B X-CRM114-Status: GOOD ( 11.24 ) X-BeenThere: linux-amlogic@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-amlogic" Errors-To: linux-amlogic-bounces+linux-amlogic=archiver.kernel.org@lists.infradead.org Hi Andy, Thank you for your advice. On 2022/4/18 20:09, Andy Shevchenko wrote: > [ EXTERNAL EMAIL ] > > On Mon, Apr 18, 2022 at 8:50 AM Yu Tu wrote: >> >> A /2 divider over XTAL was introduced since G12A, and is preferred >> to be used over the still present /3 divider since it provides much >> closer frequencies vs the request baudrate.Especially the BT module > > 'e. E' (mind the space) My statement is a whole. There should be no spaces. > >> uses 3Mhz baud rate. 8Mhz calculations can lead to baud rate bias, >> causing some problems. > > ... > >> +struct meson_uart_data { >> + bool has_xtal_div2; > > I would prefer to see this as an unsigned int and with a less > particular name, e.g. xtal_div would suffice. I don't have a problem with your suggestion.Let's see What Neil has to say. > >> +}; > > ... > >> + unsigned int xtal_div = 3; > >> + if (private_data && private_data->has_xtal_div2) { >> + xtal_div = 2; > > Better to define privata data always > > >> + val |= AML_UART_BAUD_XTAL_DIV2; >> + } >> + val |= DIV_ROUND_CLOSEST(port->uartclk / xtal_div, baud) - 1; > > _______________________________________________ linux-amlogic mailing list linux-amlogic@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-amlogic