From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754802Ab1AFW2a (ORCPT ); Thu, 6 Jan 2011 17:28:30 -0500 Received: from kroah.org ([198.145.64.141]:55669 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754542Ab1AFWXu (ORCPT ); Thu, 6 Jan 2011 17:23:50 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Yegor Yefremov , Yegor Yefremov , Greg Kroah-Hartman Subject: [PATCH 20/36] RS485 documentation: add 16C950 UART description Date: Thu, 6 Jan 2011 14:23:09 -0800 Message-Id: <1294352605-31906-20-git-send-email-gregkh@suse.de> X-Mailer: git-send-email 1.7.3.2 In-Reply-To: <20110106215404.GA30624@kroah.com> References: <20110106215404.GA30624@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yegor Yefremov Add a notion about 16C950 UART, that is using DTR signal for RS485 mode. Signed-off-by: Yegor Yefremov Signed-off-by: Greg Kroah-Hartman --- Documentation/serial/serial-rs485.txt | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/Documentation/serial/serial-rs485.txt b/Documentation/serial/serial-rs485.txt index a3b1af7..a493238 100644 --- a/Documentation/serial/serial-rs485.txt +++ b/Documentation/serial/serial-rs485.txt @@ -11,10 +11,11 @@ 2. HARDWARE-RELATED CONSIDERATIONS - Some CPUs (e.g., Atmel AT91) contain a built-in half-duplex mode capable of - automatically controlling line direction by toggling RTS. That can used to - control external half-duplex hardware like an RS485 transceiver or any - RS232-connected half-duplex device like some modems. + Some CPUs/UARTs (e.g., Atmel AT91 or 16C950 UART) contain a built-in + half-duplex mode capable of automatically controlling line direction by + toggling RTS or DTR signals. That can be used to control external + half-duplex hardware like an RS485 transceiver or any RS232-connected + half-duplex devices like some modems. For these microcontrollers, the Linux driver should be made capable of working in both modes, and proper ioctls (see later) should be made -- 1.7.3.2