From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758121AbZJNSoy (ORCPT ); Wed, 14 Oct 2009 14:44:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756943AbZJNSox (ORCPT ); Wed, 14 Oct 2009 14:44:53 -0400 Received: from kcmailp07.birch.net ([216.212.0.102]:50035 "EHLO mx01.birch.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756566AbZJNSow (ORCPT ); Wed, 14 Oct 2009 14:44:52 -0400 Message-ID: <4AD61BFE.2000607@softplc.com> Date: Wed, 14 Oct 2009 13:44:14 -0500 From: Dick Hollenbeck User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Subject: [PATCH] 8250 serial transmitter fully empty test Content-Type: multipart/mixed; boundary="------------040501080904040405040505" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------040501080904040405040505 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit When controlling an industrial radio modem it can be necessary to manipulate the handshake lines in order to control the radio modem's transmitter, from userspace. The transmitter should not be turned off before all characters have been transmitted. serial8250_tx_empty() was reporting that all characters were transmitted before they actually were. Signed-off-by: Dick Hollenbeck --------------040501080904040405040505 Content-Type: text/x-patch; name="8250.diff" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="8250.diff" --- drivers/serial/8250.c.orig 2009-09-26 14:06:55.000000000 -0500 +++ drivers/serial/8250.c 2009-09-26 14:12:37.000000000 -0500 @@ -81,6 +81,9 @@ static int serial_index(struct uart_port #define PASS_LIMIT 256 +#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE) + + /* * We default to IRQ0 for the "no irq" hack. Some * machine types want others as well - they're free @@ -1792,7 +1795,7 @@ static unsigned int serial8250_tx_empty( up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; spin_unlock_irqrestore(&up->port.lock, flags); - return lsr & UART_LSR_TEMT ? TIOCSER_TEMT : 0; + return (lsr & BOTH_EMPTY) == BOTH_EMPTY ? TIOCSER_TEMT : 0; } static unsigned int serial8250_get_mctrl(struct uart_port *port) @@ -1850,8 +1853,6 @@ static void serial8250_break_ctl(struct spin_unlock_irqrestore(&up->port.lock, flags); } -#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE) - /* * Wait for transmitter & holding register to empty */ --------------040501080904040405040505--