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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 262CCC04AA7 for ; Mon, 13 May 2019 15:43:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 015ED20879 for ; Mon, 13 May 2019 15:43:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728268AbfEMPnT (ORCPT ); Mon, 13 May 2019 11:43:19 -0400 Received: from relay1.mentorg.com ([192.94.38.131]:37075 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726274AbfEMPnT (ORCPT ); Mon, 13 May 2019 11:43:19 -0400 Received: from svr-orw-mbx-01.mgc.mentorg.com ([147.34.90.201]) by relay1.mentorg.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-SHA384:256) id 1hQD6c-0001Xa-5u from George_Davis@mentor.com ; Mon, 13 May 2019 08:43:10 -0700 Received: from localhost (147.34.91.1) by svr-orw-mbx-01.mgc.mentorg.com (147.34.90.201) with Microsoft SMTP Server (TLS) id 15.0.1320.4; Mon, 13 May 2019 08:43:07 -0700 Date: Mon, 13 May 2019 11:43:06 -0400 From: "George G. Davis" To: Wolfram Sang CC: "George G. Davis" , Eugeniu Rosca , Geert Uytterhoeven , Greg Kroah-Hartman , Jiri Slaby , "open list:SERIAL DRIVERS" , open list , Simon Horman , Chris Brandt , Wolfram Sang , Ulrich Hecht , Andy Lowe , Linux-Renesas , OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS , Magnus Damm , Rob Herring , Mark Rutland Subject: Re: [PATCH] serial: sh-sci: disable DMA for uart_console Message-ID: <20190513154306.GA6060@mam-gdavis-lt> References: <20190506194233.GA32430@vmlxhi-102.adit-jv.com> <1557413011-1662-1-git-send-email-george_davis@mentor.com> <20190513135114.GA20443@kunai> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20190513135114.GA20443@kunai> User-Agent: Mutt/1.5.24 (2015-08-30) X-ClientProxiedBy: svr-orw-mbx-01.mgc.mentorg.com (147.34.90.201) To svr-orw-mbx-01.mgc.mentorg.com (147.34.90.201) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Wolfram, On Mon, May 13, 2019 at 03:51:14PM +0200, Wolfram Sang wrote: > On Thu, May 09, 2019 at 10:43:30AM -0400, George G. Davis wrote: > > As noted in commit 84b40e3b57ee ("serial: 8250: omap: Disable DMA for > > console UART"), UART console lines use low-level PIO only access functions > > which will conflict with use of the line when DMA is enabled, e.g. when > > the console line is also used for systemd messages. So disable DMA > > support for UART console lines. > > > > Fixes: https://patchwork.kernel.org/patch/10929511/ > > Reported-by: Michael Rodin > > Cc: Eugeniu Rosca > > Signed-off-by: George G. Davis > > --- > > drivers/tty/serial/sh-sci.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c > > index 3cd139752d3f..885b56b1d4e4 100644 > > --- a/drivers/tty/serial/sh-sci.c > > +++ b/drivers/tty/serial/sh-sci.c > > @@ -1557,6 +1557,9 @@ static void sci_request_dma(struct uart_port *port) > > > > dev_dbg(port->dev, "%s: port %d\n", __func__, port->line); > > > > + if (uart_console(port)) > > + return; /* Cannot use DMA on console */ > > Minor nit: maybe the comment can be made more specific? > > /* > * DMA on console may interfere with Kernel log messages which use > * plain putchar(). So, simply don't use it with a console. > */ I'll submit v2 with the above recommended change. Thanks! > Other than that: > > Reviewed-by: Wolfram Sang > > Much better than dropping the properties, as Geert noted. -- Regards, George