From patchwork Fri Oct 11 10:30:58 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Huang Shijie X-Patchwork-Id: 3022631 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 06896BF924 for ; Fri, 11 Oct 2013 10:48:45 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D29F820343 for ; Fri, 11 Oct 2013 10:48:43 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6FD1A20278 for ; Fri, 11 Oct 2013 10:48:42 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VUaFg-00057V-OS; Fri, 11 Oct 2013 10:47:25 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VUaFJ-0004Ks-3d; Fri, 11 Oct 2013 10:47:01 +0000 Received: from mail-db8lp0188.outbound.messaging.microsoft.com ([213.199.154.188] helo=db8outboundpool.messaging.microsoft.com) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VUaEf-0004Dm-Dh for linux-arm-kernel@lists.infradead.org; Fri, 11 Oct 2013 10:46:22 +0000 Received: from mail160-db8-R.bigfish.com (10.174.8.252) by DB8EHSOBE035.bigfish.com (10.174.4.98) with Microsoft SMTP Server id 14.1.225.22; Fri, 11 Oct 2013 10:45:52 +0000 Received: from mail160-db8 (localhost [127.0.0.1]) by mail160-db8-R.bigfish.com (Postfix) with ESMTP id E548D2E031A; Fri, 11 Oct 2013 10:45:51 +0000 (UTC) X-Forefront-Antispam-Report: CIP:70.37.183.190; KIP:(null); UIP:(null); IPV:NLI; H:mail.freescale.net; RD:none; EFVD:NLI X-SpamScore: 3 X-BigFish: VS3(zzzz1f42h208ch1ee6h1de0h1fdah2073h1202h1e76h1d1ah1d2ah1fc6h1082kzz1de098h1de097h8275bhz2dh2a8h839hd24he5bhf0ah1288h12a5h12a9h12bdh12e5h137ah139eh13b6h1441h1504h1537h162dh1631h1758h1898h18e1h1946h19b5h1ad9h1b0ah1b2fh1fb3h1d0ch1d2eh1d3fh1dfeh1dffh1e23h1fe8h1ff5h1155h) Received: from mail160-db8 (localhost.localdomain [127.0.0.1]) by mail160-db8 (MessageSwitch) id 1381488349969325_1362; Fri, 11 Oct 2013 10:45:49 +0000 (UTC) Received: from DB8EHSMHS017.bigfish.com (unknown [10.174.8.241]) by mail160-db8.bigfish.com (Postfix) with ESMTP id E830FD80040; Fri, 11 Oct 2013 10:45:49 +0000 (UTC) Received: from mail.freescale.net (70.37.183.190) by DB8EHSMHS017.bigfish.com (10.174.4.27) with Microsoft SMTP Server (TLS) id 14.16.227.3; Fri, 11 Oct 2013 10:45:49 +0000 Received: from az84smr01.freescale.net (10.64.34.197) by 039-SN1MMR1-004.039d.mgd.msft.net (10.84.1.14) with Microsoft SMTP Server (TLS) id 14.3.158.2; Fri, 11 Oct 2013 10:45:48 +0000 Received: from shlinux2.ap.freescale.net (shlinux2.ap.freescale.net [10.192.224.44]) by az84smr01.freescale.net (8.14.3/8.14.0) with ESMTP id r9BAjhBF018398; Fri, 11 Oct 2013 03:45:46 -0700 From: Huang Shijie To: Subject: [PATCH 1/4] serial: imx: implement the flush_buffer hook Date: Fri, 11 Oct 2013 18:30:58 +0800 Message-ID: <1381487461-12850-2-git-send-email-b32955@freescale.com> X-Mailer: git-send-email 1.7.2.rc3 In-Reply-To: <1381487461-12850-1-git-send-email-b32955@freescale.com> References: <1381487461-12850-1-git-send-email-b32955@freescale.com> MIME-Version: 1.0 X-OriginatorOrg: freescale.com X-FOPE-CONNECTOR: Id%0$Dn%*$RO%0$TLS%0$FQDN%$TlsDn% X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20131011_064621_712854_C968F3E3 X-CRM114-Status: GOOD ( 13.12 ) X-Spam-Score: -1.9 (-) Cc: Huang Shijie , shawn.guo@linaro.org, linux-arm-kernel@lists.infradead.org, linux-serial@vger.kernel.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The current driver does not implement the flush_buffer hook for uart_ops. When we enable the DMA for the driver, and test it with Bluetooth, we may meet the following bug for TX: [1] User application may call the flush operation at any time. The uart_flush_buffer() calls the uart_circ_clear() to set the xmit->head and xmit->tail with 0. [2] The TX DMA callback can be called at any time too. The dma_tx_call() will update the xmit->tail. If [2] occurs just after the [1], we will get the wrong xmit->tail. This patch implements the flush_buffer hook to fix this issue. Signed-off-by: Huang Shijie --- drivers/tty/serial/imx.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index c07d9bb..708ba89 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1303,6 +1303,16 @@ static void imx_shutdown(struct uart_port *port) clk_disable_unprepare(sport->clk_ipg); } +static void imx_flush_buffer(struct uart_port *port) +{ + struct imx_port *sport = (struct imx_port *)port; + + if (sport->dma_is_enabled) { + sport->tx_bytes = 0; + dmaengine_terminate_all(sport->dma_chan_tx); + } +} + static void imx_set_termios(struct uart_port *port, struct ktermios *termios, struct ktermios *old) @@ -1623,6 +1633,7 @@ static struct uart_ops imx_pops = { .break_ctl = imx_break_ctl, .startup = imx_startup, .shutdown = imx_shutdown, + .flush_buffer = imx_flush_buffer, .set_termios = imx_set_termios, .type = imx_type, .release_port = imx_release_port,