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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 115B6C76195 for ; Fri, 19 Jul 2019 03:58:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D293321851 for ; Fri, 19 Jul 2019 03:58:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563508721; bh=GLbL3FyzfUad1Fjle5j4mAmrF0o2jqKJECEIfieDOOU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=etiiIgEKqCqRBllwxXkSEiHmicDTKLp2hZbv39z/kX0UEofsaDYJRGE6T7GEw7XDF W++nRk3xDt3xh8MRei6CZ/gvGr9Khn8iyBrDQzkg6QfVPuwj4zFdwqG6rg1ds6dCVI b/a9DbGBQTwop7vJaY0JjBFpud9fDLtEoEyHdk0M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728222AbfGSD6l (ORCPT ); Thu, 18 Jul 2019 23:58:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:58014 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728175AbfGSD6h (ORCPT ); Thu, 18 Jul 2019 23:58:37 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9666121871; Fri, 19 Jul 2019 03:58:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563508716; bh=GLbL3FyzfUad1Fjle5j4mAmrF0o2jqKJECEIfieDOOU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mKK8Lo2T32npFi3889HRDI7uWhdmnyRQeKoVfRVQoFCxPsLi1t+9LUw/f33+q8uHa aYBQYKTuN8tbrHwJLrzUZkn40lB0V6IyUUJlV+TX99m8TAizhEqvLuca1yv5XL8czh CTxUkZUcGdcOMzYBzRSEAsd3PGw9KX/qOP+bwz88= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Rautkoski Kimmo EXT , Greg Kroah-Hartman , Sasha Levin , linux-serial@vger.kernel.org Subject: [PATCH AUTOSEL 5.2 050/171] serial: 8250: Fix TX interrupt handling condition Date: Thu, 18 Jul 2019 23:54:41 -0400 Message-Id: <20190719035643.14300-50-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190719035643.14300-1-sashal@kernel.org> References: <20190719035643.14300-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rautkoski Kimmo EXT [ 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