From mboxrd@z Thu Jan 1 00:00:00 1970 From: Huang Shijie Subject: Re: [PATCH 1/2] serial: imx: remove the DMA wait queue Date: Fri, 30 May 2014 17:01:30 +0800 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" Return-path: 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 Content-Disposition: inline In-Reply-To: <857E9EDCA6C0904DB3357321AA9123EBE14B5A2C@NA-MBX-03.mgc.mentorg.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org 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" 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