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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A7A2C433EF for ; Thu, 7 Apr 2022 08:31:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243028AbiDGIdB (ORCPT ); Thu, 7 Apr 2022 04:33:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32806 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243036AbiDGIc2 (ORCPT ); Thu, 7 Apr 2022 04:32:28 -0400 Received: from mail-sh.amlogic.com (mail-sh.amlogic.com [58.32.228.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 181B3152823; Thu, 7 Apr 2022 01:30:28 -0700 (PDT) Received: from droid06.amlogic.com (10.18.11.248) by mail-sh.amlogic.com (10.18.11.5) with Microsoft SMTP Server id 15.1.2176.14; Thu, 7 Apr 2022 16:15:22 +0800 From: Yu Tu To: , , , , Neil Armstrong , Kevin Hilman , Jerome Brunet CC: Greg Kroah-Hartman , Jiri Slaby , Martin Blumenstingl , Yu Tu Subject: [PATCH 1/3] tty: serial: meson: Use DIV_ROUND_CLOSEST to calculate baud rates Date: Thu, 7 Apr 2022 16:13:53 +0800 Message-ID: <20220407081355.13602-2-yu.tu@amlogic.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20220407081355.13602-1-yu.tu@amlogic.com> References: <20220407081355.13602-1-yu.tu@amlogic.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.18.11.248] Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Due to chip process differences, chip designers recommend using baud rates as close to and larger as possible in order to reduce clock errors. Signed-off-by: Yu Tu --- drivers/tty/serial/meson_uart.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c index 2bf1c57e0981..8e59624935af 100644 --- a/drivers/tty/serial/meson_uart.c +++ b/drivers/tty/serial/meson_uart.c @@ -299,10 +299,10 @@ static void meson_uart_change_speed(struct uart_port *port, unsigned long baud) cpu_relax(); if (port->uartclk == 24000000) { - val = ((port->uartclk / 3) / baud) - 1; + val = DIV_ROUND_CLOSEST(port->uartclk / 3, baud) - 1; val |= AML_UART_BAUD_XTAL; } else { - val = ((port->uartclk * 10 / (baud * 4) + 5) / 10) - 1; + val = DIV_ROUND_CLOSEST(port->uartclk / 4, baud) - 1; } val |= AML_UART_BAUD_USE; writel(val, port->membase + AML_UART_REG5); -- 2.33.1