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 1B1F9C433F5 for ; Thu, 21 Apr 2022 08:47:10 +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=WnxtE9Z8tv7aa7PbrVrOwF2u5bWQh+PAl2AoyItnfMs=; b=QGgy6c3bbn3gKX mcYW9HxJK9mQBjWmZgIEUcbF2oxgmEetJqGDSAIeN7uFDD/d83y5219An0eRiiuO0Lf5mAWgImIrU 2geSo4St+oWpbMvGeOQJP5+J6Nh9ui5kPEYw/2cjatI+EQPzqtZ8Ndmk7nQAySRtQc1a+PDazaoq+ tQZsahOkeW8XOsDbhghb2mkLMT0Ucj391KK0qLPbolPw6lQ5YM1VkquFSk0yyceDpXQ9SsY67NkBW W6+R1gkmABafkYDC+o/z45+SkQFiqrAaY1s2SjpkGC6TxOd7yuLEOmy6+PmYWidOIIG8CHnDQ4CZh StLtxly7AG1TMjbDhnyw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nhSSu-00CUs5-FP; Thu, 21 Apr 2022 08:47:04 +0000 Received: from mail-wr1-x42c.google.com ([2a00:1450:4864:20::42c]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nhSSi-00CUo3-HM for linux-amlogic@lists.infradead.org; Thu, 21 Apr 2022 08:46:53 +0000 Received: by mail-wr1-x42c.google.com with SMTP id i20so5614355wrb.13 for ; Thu, 21 Apr 2022 01:46:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:organization:in-reply-to :content-transfer-encoding; bh=Z1R8XAgRO1RY9ptbheHK+UH29R2eRMz8Ro595MvYVes=; b=aOom/33qqLb3Lfu2zcsAjrk7UdXHJJVRy0kJNKJDjgPslzoTYHMMljkC085jJpJYR4 EegA7KKwIkF+/1WfHa3PQDt8NPu1ipsKPgiV9Avgu/YlXoYfX3R3pVRdtMLK0PAE95+G UHsar2YSfO7sL93bYGnai0RpaCTbEzQAbufLW2NgH5woKN7/5vWtjkeIg6qBaVFU9VPh Er2VeFX0ErcmUSIvBehlMeYXwv74Smim+58XkpaLUxJJBJDykvoLxNjR1g9kU7+ERwWU wOq/Kfa6Rk9IbqfWUUDvnYA5BPRNIkFSag2Qr75UmCf3pYTGplwMsiLgofgIOxNEtMbH LLww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:organization:in-reply-to :content-transfer-encoding; bh=Z1R8XAgRO1RY9ptbheHK+UH29R2eRMz8Ro595MvYVes=; b=lyeljPA8J6VQRxsSFzPsTmE2z+fk8bQyc6pppYh+o4BMuOZMOA7hHvXhFIj4XQVX6t +HB++E4TDTTs3WrQczPuDAtSFm9C4ZNyWmNxTX+dsGGauXTrbRkzNi/mzz3V/yqV5eKA kvLHguWVJVWSi90ncmplLAw85w83SK/QBvXw5K4BxkGcn9mi6ZJObITNG/cixgf4MWbR FAS7b5Tn7788bYGwU7GCP5aYxb6nV7fs3X8SGrFpJERGNiYd1usgYcOyOGauwtRvpjqD xygBgloAyyBmU4No/s6YxiznKIQcXqPJeAEV8bl4IdOvPgMfQmTXZfDWQ0dlVo/WN0O2 wmaQ== X-Gm-Message-State: AOAM531CN4PEU5/QXL6HvSCjvgFFGiKfjcSkkaW+fVkj/pV2TmJdA2Hs rcsnIySXcp3yjvRloG5wnle/gA== X-Google-Smtp-Source: ABdhPJzkRWJgbzkZ114xvkXhqIqlkVxz401XfIJZslOH3Cuuu/rWZ1ncxnciYetQhmsi7vVlYYPT2w== X-Received: by 2002:a05:6000:c4:b0:20a:bfeb:68dc with SMTP id q4-20020a05600000c400b0020abfeb68dcmr1261741wrx.488.1650530810597; Thu, 21 Apr 2022 01:46:50 -0700 (PDT) Received: from ?IPV6:2001:861:44c0:66c0:35ba:2677:956:980d? ([2001:861:44c0:66c0:35ba:2677:956:980d]) by smtp.gmail.com with ESMTPSA id b14-20020a7bc24e000000b003899c8053e1sm1675671wmj.41.2022.04.21.01.46.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Apr 2022 01:46:50 -0700 (PDT) Message-ID: Date: Thu, 21 Apr 2022 10:46:57 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; 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 , Yu Tu Cc: "open list:SERIAL DRIVERS" , linux-arm Mailing List , linux-amlogic , Linux Kernel Mailing List , Greg Kroah-Hartman , Kevin Hilman , Jerome Brunet , Jiri Slaby , Martin Blumenstingl References: <20220418053202.24528-1-yu.tu@amlogic.com> <20220418053202.24528-2-yu.tu@amlogic.com> From: Neil Armstrong Organization: Baylibre In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220421_014652_628407_73FFC2E8 X-CRM114-Status: GOOD ( 14.63 ) 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, On 18/04/2022 14:09, Andy Shevchenko wrote: > 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) > >> 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. > >> +}; > > ... > >> + unsigned int xtal_div = 3; > >> + if (private_data && private_data->has_xtal_div2) { >> + xtal_div = 2; > > Better to define privata data always While I'm in favor of defining private data, here 3 and 2 are actually the values 2 and 3 used to divide. The code is easy to read and we quickly understand this value is the clock divider. > > >> + 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