From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932803AbaE3KXF (ORCPT ); Fri, 30 May 2014 06:23:05 -0400 Received: from mail-bn1blp0186.outbound.protection.outlook.com ([207.46.163.186]:57959 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755275AbaE3KXD (ORCPT ); Fri, 30 May 2014 06:23:03 -0400 Date: Fri, 30 May 2014 17:01:30 +0800 From: Huang Shijie To: "Wang, Jiada (ESD)" CC: "gregkh@linuxfoundation.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-serial@vger.kernel.org" , "Behme, Dirk - Bosch" Subject: Re: [PATCH 1/2] serial: imx: remove the DMA wait queue Message-ID: <20140530090128.GA4380@shlinux1.ap.freescale.net> References: <1400819575-20435-1-git-send-email-b32955@freescale.com> <857E9EDCA6C0904DB3357321AA9123EBE14B5A2C@NA-MBX-03.mgc.mentorg.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <857E9EDCA6C0904DB3357321AA9123EBE14B5A2C@NA-MBX-03.mgc.mentorg.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-EOPAttributedMessage: 0 X-Forefront-Antispam-Report: CIP:192.88.168.50;CTRY:US;IPV:CAL;IPV:NLI;EFV:NLI;SFV:NSPM;SFS:(6009001)(189002)(24454002)(199002)(51704005)(50986999)(99396002)(76482001)(76176999)(83072002)(6806004)(80022001)(74502001)(83322001)(47776003)(84676001)(97736001)(44976005)(79102001)(104016001)(26826002)(31966008)(23726002)(64706001)(97756001)(68736004)(33656002)(85852003)(50466002)(81342001)(81542001)(74662001)(92566001)(21056001)(54356999)(92726001)(46102001)(87936001)(102836001)(77096999)(77982001)(20776003)(83506001)(4396001)(46406003)(42262001);DIR:OUT;SFP:;SCL:1;SRVR:DM2PR03MB367;H:tx30smr01.am.freescale.net;FPR:;MLV:ovrnspm;PTR:InfoDomainNonexistent;MX:1;A:1;LANG:en; X-Microsoft-Antispam: BL:0;ACTION:Default;RISK:Low;SCL:0;SPMLVL:NotSpam;PCL:0;RULEID: X-Forefront-PRVS: 02272225C5 Authentication-Results: spf=fail (sender IP is 192.88.168.50) smtp.mailfrom=shijie.huang@freescale.com; X-OriginatorOrg: freescale.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 30, 2014 at 09:27:20AM +0000, Wang, Jiada (ESD) wrote: > Hi Shijie > > After apply this patch into our kernel, > We are facing data hang issue when sending big size file (2M used in test) to uart port > Note: Rx port is also keep receiving data. > > After read the implementation of uart_stop(), > I feel like, stop_tx() is used to perform flow control when like a XOFF is received. > Which means no data should be dropped, as they may need to be sent out, > When next start_tx() is called. > > But by calling dmaengine_termiate_all(), the data already be submitted to DMA engine, > May be lost, thus cause data hang. > > What do you think? This patch has been reverted by Greg. I also noticed the data loss issue. thanks Huang Shijie