Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760864AbbKTRFP (ORCPT ); Fri, 20 Nov 2015 12:05:15 -0500 Received: from mail-bl2nam02on0054.outbound.protection.outlook.com ([104.47.38.54]:59968 "EHLO NAM02-BL2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1759543AbbKTRFL (ORCPT ); Fri, 20 Nov 2015 12:05:11 -0500 Authentication-Results: spf=pass (sender IP is 149.199.60.83) smtp.mailfrom=xilinx.com; vger.kernel.org; dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=bestguesspass action=none header.from=xilinx.com; Date: Fri, 20 Nov 2015 09:05:26 -0800 From: =?utf-8?B?U8O2cmVu?= Brinkmann To: Peter Hurley CC: Greg Kroah-Hartman , Jiri Slaby , , Michal Simek , , Subject: Re: [PATH RESEND v2 03/10] tty: xuartps: Always enable transmitter in start_tx Message-ID: <20151120170525.GW32017@xsjsorenbubuntu> References: <1447963344-16266-1-git-send-email-soren.brinkmann@xilinx.com> <1447963344-16266-4-git-send-email-soren.brinkmann@xilinx.com> <564F0E75.5020100@hurleysoftware.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <564F0E75.5020100@hurleysoftware.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-RCIS-Action: ALLOW X-TM-AS-Product-Ver: IMSS-7.1.0.1224-8.0.0.1202-21952.006 X-TM-AS-User-Approved-Sender: Yes;Yes X-EOPAttributedMessage: 0 X-Forefront-Antispam-Report: CIP:149.199.60.83;CTRY:US;IPV:NLI;EFV:NLI;SFV:NSPM;SFS:(10009020)(6009001)(2980300002)(438002)(24454002)(164054003)(199003)(377424004)(189002)(377454003)(479174004)(83506001)(586003)(4001150100001)(110136002)(4001350100001)(81156007)(5001960100002)(87936001)(36386004)(23676002)(33716001)(77096005)(86362001)(47776003)(50466002)(2950100001)(189998001)(106466001)(33656002)(85182001)(85202003)(63266004)(76176999)(54356999)(5008740100001)(50986999)(57986006)(11100500001)(76506005)(6806005)(5007970100001)(92566002)(107986001)(217873001);DIR:OUT;SFP:1101;SCL:1;SRVR:CY1NAM02HT197;H:xsj-pvapsmtpgw01;FPR:;SPF:Pass;PTR:unknown-60-83.xilinx.com;A:1;MX:1;LANG:en; X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(8251501001);SRVR:CY1NAM02HT197; X-Microsoft-Antispam-PRVS: <1f64fffdc8894060af64cf9db2bd1b48@CY1NAM02HT197.eop-nam02.prod.protection.outlook.com> X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(601004)(2401047)(520078)(5005006)(8121501046)(3002001)(10201501046);SRVR:CY1NAM02HT197;BCL:0;PCL:0;RULEID:;SRVR:CY1NAM02HT197; X-Forefront-PRVS: 07665BE9D1 X-OriginatorOrg: xilinx.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Nov 2015 17:05:08.7329 (UTC) X-MS-Exchange-CrossTenant-Id: 657af505-d5df-48d0-8300-c31994686c5c X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=657af505-d5df-48d0-8300-c31994686c5c;Ip=[149.199.60.83];Helo=[xsj-pvapsmtpgw01] X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY1NAM02HT197 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1004 Lines: 26 On Fri, 2015-11-20 at 07:13AM -0500, Peter Hurley wrote: > > > On 11/19/2015 03:02 PM, Soren Brinkmann wrote: > > start_tx must start transmitting characters. Regardless of the state of > > the circular buffer, always enable the transmitter hardware. > > Why? > > Does cdns_uart_stop_tx() actually stop the transmitter so that > data remains in the transmitter? Fixing up the patch, I looked at this one. It might actually do that. Without having changed anything. The doc says: "The driver should stop transmitting characters as soon as possible.". And the implementation is really not draining any FIFO, but just disabling the transmitter. I take your question as that this might not be this way? Should stop_tx drain the FIFO first? Thanks, Sören -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/