Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758127AbZAHNSb (ORCPT ); Thu, 8 Jan 2009 08:18:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753483AbZAHNSX (ORCPT ); Thu, 8 Jan 2009 08:18:23 -0500 Received: from mercury.realtime.net ([205.238.132.86]:39979 "EHLO mercury.realtime.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753421AbZAHNSX (ORCPT ); Thu, 8 Jan 2009 08:18:23 -0500 In-Reply-To: <20090108123619.3543719f@lxorguk.ukuu.org.uk> References: <20090108123619.3543719f@lxorguk.ukuu.org.uk> Mime-Version: 1.0 (Apple Message framework v624) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <455ca36e8b5778fd4c7218ef31fca07c@bga.com> Content-Transfer-Encoding: 7bit Cc: Christian Borntraeger , Benjiman Herrenschmidt , linuxppc-dev list , Joe Peterson , lkml From: Milton Miller Subject: Re: [PATCH 1/4] hvc_console: do not set low_latency Date: Thu, 8 Jan 2009 07:25:14 -0600 To: Alan Cox X-Mailer: Apple Mail (2.624) X-Originating-IP: 205.232.218.56 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1599 Lines: 51 On Jan 8, 2009, at 6:36 AM, Alan Cox wrote: >> v2.6.16-rc1 via 33f0f88f1c51ae5c2d593d26960c760ea154c2e2 >> [PATCH] TTY layer buffering revamp >> >> added this new api. > > No - tty_flip_buffer_push is from 2.1.66 and with the same constraints > from the day it was added. > Yes but wrappers were added and this this and many ohter drivers were converted to use them: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git; a=commitdiff;h=33f0f88f1c51ae5c2d593d26960c760ea154c2e2 And they were slightly buggy leading to the buggy workaround. > >> Having the flag set for purely polled drivers will save delaying >> the work when receiving input for 1 jiffie. >> >> >> Index: work.git/drivers/char/hvc_console.c >> =================================================================== >> --- work.git.orig/drivers/char/hvc_console.c 2009-01-08 >> 03:01:24.000000000 -0600 >> +++ work.git/drivers/char/hvc_console.c 2009-01-08 03:01:51.000000000 >> -0600 >> @@ -318,7 +318,8 @@ static int hvc_open(struct tty_struct *t >> } /* else count == 0 */ >> >> tty->driver_data = hp; >> - tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */ >> + if (!hp->irq_requested) >> + tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */ >> >> hp->tty = tty; > > Looks good to me Thanks, I guess that is an Ack? milton -- 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/