From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755726AbZCQI4a (ORCPT ); Tue, 17 Mar 2009 04:56:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752304AbZCQI4W (ORCPT ); Tue, 17 Mar 2009 04:56:22 -0400 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:47819 "EHLO www.etchedpixels.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751911AbZCQI4V convert rfc822-to-8bit (ORCPT ); Tue, 17 Mar 2009 04:56:21 -0400 Date: Tue, 17 Mar 2009 08:57:14 +0000 From: Alan Cox To: Rocker Dude Cc: linux-kernel@vger.kernel.org Subject: Re: Serial Flow Control Message-ID: <20090317085714.54bcd51c@lxorguk.ukuu.org.uk> In-Reply-To: References: X-Mailer: Claws Mail 3.7.0 (GTK+ 2.14.7; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-14 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 17 Mar 2009 11:04:36 +0530 Rocker Dude wrote: > Hi All, > > I am using a powerpc8548e custom hardware and testing flow control on > it. I have cross-wired the RTS/CTS of the board with my host terminal. > I find that when I am reading from the powerpc, it does not change the > CTS signal when it is running out of buffers and hence it is dropping > bytes. > > I referred to something similar at http://lkml.org/lkml/2007/7/26/46. > > Can anyone please tell me if this flow control needs to be done by the SW? Flow control needs to be enabled by the user space software (if not enabled already), managed by the line discipline and implemented by the device driver (or automatically in hardware in some cases) Basically; App "set CRTSCTS" Ldisc: buffers full/not full logic for throttling Driver: throttling events -> flow control, honour flow on write