From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753150AbcKNCE0 (ORCPT ); Sun, 13 Nov 2016 21:04:26 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:44984 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751636AbcKNCEM (ORCPT ); Sun, 13 Nov 2016 21:04:12 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Nicolas Ferre" , "Alexandre Belloni" , "Greg Kroah-Hartman" Date: Mon, 14 Nov 2016 00:14:20 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 021/346] tty/serial: atmel: fix RS485 half duplex with DMA In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.39-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Alexandre Belloni commit 0058f0871efe7b01c6f2b3046c68196ab73e96da upstream. When using DMA, half duplex doesn't work properly because rx is not stopped before starting tx. Ensure we call atmel_stop_rx() in the DMA case. Signed-off-by: Alexandre Belloni Acked-by: Nicolas Ferre Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.16: - Adjust context - Keep using UART_GET_PTSR()] Signed-off-by: Ben Hutchings --- drivers/tty/serial/atmel_serial.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -434,19 +434,21 @@ static void atmel_start_tx(struct uart_p { struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); - if (atmel_use_pdc_tx(port)) { - if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN) - /* The transmitter is already running. Yes, we - really need this.*/ - return; + if (atmel_use_pdc_tx(port) && (UART_GET_PTSR(port) + & ATMEL_PDC_TXTEN)) + /* The transmitter is already running. Yes, we + really need this.*/ + return; + if (atmel_use_pdc_tx(port) || atmel_use_dma_tx(port)) if ((atmel_port->rs485.flags & SER_RS485_ENABLED) && !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX)) atmel_stop_rx(port); + if (atmel_use_pdc_tx(port)) /* re-enable PDC transmit */ UART_PUT_PTCR(port, ATMEL_PDC_TXTEN); - } + /* Enable interrupts */ UART_PUT_IER(port, atmel_port->tx_done_mask); }