From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 9AE9EC433FF for ; Mon, 29 Jul 2019 19:47:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6A0C2205F4 for ; Mon, 29 Jul 2019 19:47:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564429668; bh=ue65A/VHffRhGxa92M9SL1+8Tm3NdmZW+uzUza6JSTo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YVglmjU1HNY94CO7xSeR7M2L1yGwJ3vXLbZRAs4yitUjE3lydi9x0zv8Bc80YWBy9 NQTd7AUAHbscROn5svUfjLH/tm9j7DtCSbw55Qvtq3xoz8RDv5jjeM33Pd6HAaHN3+ Odf2ZImoPsZ9dD2hyM3lDBeAuNNOnVx3+ys9DB2g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390378AbfG2Trr (ORCPT ); Mon, 29 Jul 2019 15:47:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:37334 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389978AbfG2Trf (ORCPT ); Mon, 29 Jul 2019 15:47:35 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 141FC20C01; Mon, 29 Jul 2019 19:47:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564429654; bh=ue65A/VHffRhGxa92M9SL1+8Tm3NdmZW+uzUza6JSTo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FoRGB1gHhhFp8Q8P5V0dsFDoBFdvK3wwfaeuDBC91jYyhbpKiO1Vpnkgb1xSH4hmT ssENsXRl4y7aHi+nXAMo5MprL1y+NGRL2w3i5mJHjK+cXfTtpgMHgp1Dxa7x8X755j rBluCRwrAl8Yl5tSLv+4O6m+QRUUkLiOwi4nqvVU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kimmo Rautkoski , Sasha Levin Subject: [PATCH 5.2 052/215] serial: 8250: Fix TX interrupt handling condition Date: Mon, 29 Jul 2019 21:20:48 +0200 Message-Id: <20190729190749.568119012@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190729190739.971253303@linuxfoundation.org> References: <20190729190739.971253303@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit db1b5bc047b3cadaedab3826bba82c3d9e023c4b ] Interrupt handler checked THRE bit (transmitter holding register empty) in LSR to detect if TX fifo is empty. In case when there is only receive interrupts the TX handling got called because THRE bit in LSR is set when there is no transmission (FIFO empty). TX handling caused TX stop, which in RS-485 half-duplex mode actually resets receiver FIFO. This is not desired during reception because of possible data loss. The fix is to check if THRI is set in IER in addition of the TX fifo status. THRI in IER is set when TX is started and cleared when TX is stopped. This ensures that TX handling is only called when there is really transmission on going and an interrupt for THRE and not when there are only RX interrupts. Signed-off-by: Kimmo Rautkoski Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/8250/8250_port.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 682300713be4..eb2e2d141c01 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1874,7 +1874,8 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir) status = serial8250_rx_chars(up, status); } serial8250_modem_status(up); - if ((!up->dma || up->dma->tx_err) && (status & UART_LSR_THRE)) + if ((!up->dma || up->dma->tx_err) && (status & UART_LSR_THRE) && + (up->ier & UART_IER_THRI)) serial8250_tx_chars(up); uart_unlock_and_check_sysrq(port, flags); -- 2.20.1