Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757743AbcDGUiz (ORCPT ); Thu, 7 Apr 2016 16:38:55 -0400 Received: from mga09.intel.com ([134.134.136.24]:25952 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757548AbcDGUhX (ORCPT ); Thu, 7 Apr 2016 16:37:23 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,449,1455004800"; d="scan'208";a="682610501" From: Andy Shevchenko To: Vinod Koul , linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, Greg Kroah-Hartman , ismo.puustinen@intel.com, Heikki Krogerus , linux-serial@vger.kernel.org Cc: Andy Shevchenko Subject: [PATCH v1 08/12] serial: 8250: enable AFE on ports where FIFO is 16 bytes Date: Thu, 7 Apr 2016 23:37:09 +0300 Message-Id: <1460061433-63750-9-git-send-email-andriy.shevchenko@linux.intel.com> X-Mailer: git-send-email 2.8.0.rc3 In-Reply-To: <1460061433-63750-1-git-send-email-andriy.shevchenko@linux.intel.com> References: <1460061433-63750-1-git-send-email-andriy.shevchenko@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1336 Lines: 30 Intel Quark has 16550A compatible UART with autoflow feature enabled. It has only 16 bytes of FIFO. Currently serial8250_do_set_termios() prevents to enable autoflow since the minimum requirement of 32 bytes of FIFO size. Decrease a FIFO size limitation to 16 bytes to allow autoflow control be enabled on such UARTs. Signed-off-by: Andy Shevchenko --- drivers/tty/serial/8250/8250_port.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index e213da0..3f8121e 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2522,9 +2522,9 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, * the trigger, or the MCR RTS bit is cleared. In the case where * the remote UART is not using CTS auto flow control, we must * have sufficient FIFO entries for the latency of the remote - * UART to respond. IOW, at least 32 bytes of FIFO. + * UART to respond. IOW, at least 16 bytes of FIFO. */ - if (up->capabilities & UART_CAP_AFE && port->fifosize >= 32) { + if (up->capabilities & UART_CAP_AFE && port->fifosize >= 16) { up->mcr &= ~UART_MCR_AFE; if (termios->c_cflag & CRTSCTS) up->mcr |= UART_MCR_AFE; -- 2.8.0.rc3