From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751032AbXHJVlr (ORCPT ); Fri, 10 Aug 2007 17:41:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755134AbXHJVjU (ORCPT ); Fri, 10 Aug 2007 17:39:20 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:57124 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753545AbXHJVjR (ORCPT ); Fri, 10 Aug 2007 17:39:17 -0400 Message-Id: <200708102138.l7ALcfhb010811@imap1.linux-foundation.org> Subject: [patch 1/6] serial: don't optimise away baud rate changes when BOTHER is used To: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, dwmw2@infradead.org, alan@redhat.com, m.kozlowski@tuxland.pl, rmk@arm.linux.org.uk From: akpm@linux-foundation.org Date: Fri, 10 Aug 2007 14:38:41 -0700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: David Woodhouse The uart_set_termios() function will bail out early without bothering to touch the hardware, if it decides that nothing "relevant" has changed. Unfortunately, its idea of "relevant" doesn't include c_[io]speed. So if the baud rate bits are BOTHER and you just change the speed, the change gets optimised away. This patch makes it ignore the old Bfoo bits in c_cflag and just check whether c_ispeed and c_ospeed have changed. Those integers are always set appropriately for us by set_termios(). Signed-off-by: David Woodhouse Acked-by: Alan Cox Cc: Russell King Cc: Mariusz Kozlowski Signed-off-by: Andrew Morton --- drivers/serial/serial_core.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-) diff -puN drivers/serial/serial_core.c~dont-optimise-away-baud-rate-changes-when-bother-is-used drivers/serial/serial_core.c --- a/drivers/serial/serial_core.c~dont-optimise-away-baud-rate-changes-when-bother-is-used +++ a/drivers/serial/serial_core.c @@ -1146,11 +1146,14 @@ static void uart_set_termios(struct tty_ /* * These are the bits that are used to setup various - * flags in the low level driver. + * flags in the low level driver. We can ignore the Bfoo + * bits in c_cflag; c_[io]speed will always be set + * appropriately by set_termios() in tty_ioctl.c */ #define RELEVANT_IFLAG(iflag) ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK)) - if ((cflag ^ old_termios->c_cflag) == 0 && + tty->termios->c_ospeed == old_termios->c_ospeed && + tty->termios->c_ispeed == old_termios->c_ispeed && RELEVANT_IFLAG(tty->termios->c_iflag ^ old_termios->c_iflag) == 0) return; _