Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968178AbXFHLPH (ORCPT ); Fri, 8 Jun 2007 07:15:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966473AbXFHLO4 (ORCPT ); Fri, 8 Jun 2007 07:14:56 -0400 Received: from canuck.infradead.org ([209.217.80.40]:40776 "EHLO canuck.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966359AbXFHLOz (ORCPT ); Fri, 8 Jun 2007 07:14:55 -0400 Subject: [SERIAL] Don't optimise away baud rate changes when BOTHER is used (v2) From: David Woodhouse To: Alan Cox Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, paulus@samba.org In-Reply-To: <1181133010.4096.26.camel@pmac.infradead.org> References: <20070523172739.1d3a918c@the-village.bc.nu> <1180012135.8303.89.camel@shinybook.infradead.org> <20070524144109.7bd0f4d0@the-village.bc.nu> <1180014338.8303.95.camel@shinybook.infradead.org> <20070524160559.54c2c639@the-village.bc.nu> <1181133010.4096.26.camel@pmac.infradead.org> Content-Type: text/plain Date: Fri, 08 Jun 2007 12:14:49 +0100 Message-Id: <1181301289.2801.26.camel@pmac.infradead.org> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 (2.10.1-17.fc7.dwmw2.1) Content-Transfer-Encoding: 7bit X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. X-SRS-Rewrite: SMTP reverse-path rewritten from by canuck.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1924 Lines: 50 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(). This version of the patch lacks the debugging printk which I accidentally left in the previous one. Signed-off-by: David Woodhouse diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c index e8be3b5..4480990 100644 --- a/drivers/serial/serial_core.c +++ b/drivers/serial/serial_core.c @@ -1146,11 +1146,19 @@ static void uart_set_termios(struct tty_struct *tty, struct ktermios *old_termio /* * 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 */ +#ifdef CIBAUD +#define RELEVANT_CFLAG(cflag) ((cflag) & ~(CIBAUD|CBAUD) +#else +#define RELEVANT_CFLAG(cflag) ((cflag) & ~(CIBAUD|CBAUD) +#endif #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; -- dwmw2 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/