From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423209AbcE3VWc (ORCPT ); Mon, 30 May 2016 17:22:32 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53398 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423028AbcE3VLS (ORCPT ); Mon, 30 May 2016 17:11:18 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexandre Belloni , Nicolas Ferre Subject: [PATCH 4.6 070/100] tty/serial: atmel: fix hardware handshake selection Date: Mon, 30 May 2016 13:50:05 -0700 Message-Id: <20160530204910.694722394@linuxfoundation.org> X-Mailer: git-send-email 2.8.3 In-Reply-To: <20160530204908.422037419@linuxfoundation.org> References: <20160530204908.422037419@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexandre Belloni commit 5be605ac9af979265d7b64c160ad9928088a78be upstream. Commit 1cf6e8fc8341 ("tty/serial: at91: fix RTS line management when hardware handshake is enabled") actually allowed to enable hardware handshaking. Before, the CRTSCTS flags was silently ignored. As the DMA controller can't drive RTS (as explain in the commit message). Ensure that hardware flow control stays disabled when DMA is used and FIFOs are not available. Signed-off-by: Alexandre Belloni Acked-by: Nicolas Ferre Fixes: 1cf6e8fc8341 ("tty/serial: at91: fix RTS line management when hardware handshake is enabled") Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/atmel_serial.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -274,6 +274,13 @@ static bool atmel_use_dma_rx(struct uart return atmel_port->use_dma_rx; } +static bool atmel_use_fifo(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + + return atmel_port->fifo_size; +} + static unsigned int atmel_get_lines_status(struct uart_port *port) { struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); @@ -2090,7 +2097,12 @@ static void atmel_set_termios(struct uar mode |= ATMEL_US_USMODE_RS485; } else if (termios->c_cflag & CRTSCTS) { /* RS232 with hardware handshake (RTS/CTS) */ - mode |= ATMEL_US_USMODE_HWHS; + if (atmel_use_dma_rx(port) && !atmel_use_fifo(port)) { + dev_info(port->dev, "not enabling hardware flow control because DMA is used"); + termios->c_cflag &= ~CRTSCTS; + } else { + mode |= ATMEL_US_USMODE_HWHS; + } } else { /* RS232 without hadware handshake */ mode |= ATMEL_US_USMODE_NORMAL;