From patchwork Tue May 10 16:09:40 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Abhishek Sahu X-Patchwork-Id: 9060021 Return-Path: X-Original-To: patchwork-dmaengine@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 02A049F1C1 for ; Tue, 10 May 2016 16:10:37 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 29C09200DB for ; Tue, 10 May 2016 16:10:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5A2F20142 for ; Tue, 10 May 2016 16:10:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752428AbcEJQKe (ORCPT ); Tue, 10 May 2016 12:10:34 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:39277 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751894AbcEJQKd (ORCPT ); Tue, 10 May 2016 12:10:33 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id ECB6C6131B; Tue, 10 May 2016 16:10:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from chewinlnx07.qualcomm.com (unknown [202.46.23.62]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: absahu@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 0EE5660386; Tue, 10 May 2016 16:10:25 +0000 (UTC) From: Abhishek Sahu To: agross@codeaurora.org, david.brown@linaro.org, andy.gross@linaro.org, gregkh@linuxfoundation.org Cc: jslaby@suse.com, linux-soc@vger.kernel.org, linux-serial@vger.kernel.org, sricharan@codeaurora.org, architt@codeaurora.org, linux-arm-msm@vger.kernel.org, ntelkar@codeaurora.org, galak@codeaurora.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Charanya , Abhishek Sahu Subject: [PATCH] tty: serial: msm: Disable restoring Rx interrupts for DMA Mode Date: Tue, 10 May 2016 21:39:40 +0530 Message-Id: <1462896580-11554-1-git-send-email-absahu@codeaurora.org> X-Mailer: git-send-email 1.9.1 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Charanya The Data loss was happening with current QCOM MSM serial driver during large file transfer due to simultaneous enabling of both UART and DMA interrupt. When UART operates in DMA mode, RXLEV (Rx FIFO over watermark) or RXSTALE (stale interrupts) should not be enabled, since these conditions will be handled by DMA controller itself. If these interrupts are enabled then normal UART ISR will read some bytes of data from Rx Buffer and DMA controller will not receive these bytes of data, which will cause data loss. Now this patch removed the code for enabling of RXLEV and RXSTALE interrupt in DMA Rx completion routine. Signed-off-by: Charanya Signed-off-by: Abhishek Sahu --- drivers/tty/serial/msm_serial.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index 96d3ce8..6262b18 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -388,10 +388,6 @@ static void msm_complete_rx_dma(void *args) val &= ~dma->enable_bit; msm_write(port, val, UARTDM_DMEN); - /* Restore interrupts */ - msm_port->imr |= UART_IMR_RXLEV | UART_IMR_RXSTALE; - msm_write(port, msm_port->imr, UART_IMR); - if (msm_read(port, UART_SR) & UART_SR_OVERRUN) { port->icount.overrun++; tty_insert_flip_char(tport, 0, TTY_OVERRUN);