From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752538AbZJ1SIf (ORCPT ); Wed, 28 Oct 2009 14:08:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751915AbZJ1SIf (ORCPT ); Wed, 28 Oct 2009 14:08:35 -0400 Received: from kroah.org ([198.145.64.141]:42080 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751857AbZJ1SIe (ORCPT ); Wed, 28 Oct 2009 14:08:34 -0400 Date: Wed, 28 Oct 2009 11:05:44 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, Alan Cox Subject: Re: Dropped characters in serial connection without flow control Message-ID: <20091028180544.GA3523@kroah.com> References: <20091028175937.27472.qmail@stuge.se> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091028175937.27472.qmail@stuge.se> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 28, 2009 at 06:59:37PM +0100, Peter Stuge wrote: > Peter Stuge wrote: > > I'm writing a line discipline for a serial port multiplexing > > hardware > > There is no(!) support for flow control in the hardware. > > Is there anything I can do to reduce serial port interrupt latency or > otherwise try to mitigate this in my ldisc or in Linux in general? I > realize that it will never be quite reliable without any flow > control. What's wrong with XON/XOFF? That is a well-known flow control protocol for systems without hardware support for it. And since when is adding a UART to a hardware chip expensive these days? thanks, greg k-h