From patchwork Tue Aug 10 17:30:35 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 495866 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35C48C43214 for ; Tue, 10 Aug 2021 17:40:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1CA2E6115B for ; Tue, 10 Aug 2021 17:40:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234349AbhHJRkV (ORCPT ); Tue, 10 Aug 2021 13:40:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:42010 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233409AbhHJRgl (ORCPT ); Tue, 10 Aug 2021 13:36:41 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B6D96610EA; Tue, 10 Aug 2021 17:35:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1628616944; bh=xHgfxz9wQATRqOjex35VnVIrpDufuV1SvTgYhWBlqA4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ou/TInDv+Rx0W2yVHFgKrMjFuhDsWgh6gHjY0XPUG2EzTDEX6HLJtBhvOF0pjFH7e ssFhe1DfQUWvq06oBYSaHQpVnypQj9Bq/ODnwzT7ylOh4I8sWMzWPDiO16UT1T08zq 2XCeDkXG28N5zMRvIDtZe2mfagmvNPZT2JzMmbAE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zhiyong Tao Subject: [PATCH 5.4 62/85] serial: 8250_mtk: fix uart corruption issue when rx power off Date: Tue, 10 Aug 2021 19:30:35 +0200 Message-Id: <20210810172950.339027962@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210810172948.192298392@linuxfoundation.org> References: <20210810172948.192298392@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Zhiyong Tao commit 7c4a509d3815a260c423c0633bd73695250ac26d upstream. Fix uart corruption issue when rx power off. Add spin lock in mtk8250_dma_rx_complete function in APDMA mode. when uart is used as a communication port with external device(GPS). when external device(GPS) power off, the power of rx pin is also from 1.8v to 0v. Even if there is not any data in rx. But uart rx pin can capture the data "0". If uart don't receive any data in specified cycle, uart will generates BI(Break interrupt) interrupt. If external device(GPS) power off, we found that BI interrupt appeared continuously and very frequently. When uart interrupt type is BI, uart IRQ handler(8250 framwork API:serial8250_handle_irq) will push data to tty buffer. mtk8250_dma_rx_complete is a task of mtk_uart_apdma_rx_handler. mtk8250_dma_rx_complete priority is lower than uart irq handler(serial8250_handle_irq). if we are in process of mtk8250_dma_rx_complete, uart appear BI interrupt:1)serial8250_handle_irq will priority execution.2)it may cause write tty buffer conflict in mtk8250_dma_rx_complete. So the spin lock protect the rx receive data process is not break. Signed-off-by: Zhiyong Tao Cc: stable Link: https://lore.kernel.org/r/20210729084640.17613-2-zhiyong.tao@mediatek.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_mtk.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/drivers/tty/serial/8250/8250_mtk.c +++ b/drivers/tty/serial/8250/8250_mtk.c @@ -92,10 +92,13 @@ static void mtk8250_dma_rx_complete(void struct dma_tx_state state; int copied, total, cnt; unsigned char *ptr; + unsigned long flags; if (data->rx_status == DMA_RX_SHUTDOWN) return; + spin_lock_irqsave(&up->port.lock, flags); + dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state); total = dma->rx_size - state.residue; cnt = total; @@ -119,6 +122,8 @@ static void mtk8250_dma_rx_complete(void tty_flip_buffer_push(tty_port); mtk8250_rx_dma(up); + + spin_unlock_irqrestore(&up->port.lock, flags); } static void mtk8250_rx_dma(struct uart_8250_port *up)