From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756387AbZHMVav (ORCPT ); Thu, 13 Aug 2009 17:30:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752755AbZHMVav (ORCPT ); Thu, 13 Aug 2009 17:30:51 -0400 Received: from kroah.org ([198.145.64.141]:47165 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752515AbZHMVau (ORCPT ); Thu, 13 Aug 2009 17:30:50 -0400 Date: Thu, 13 Aug 2009 14:27:50 -0700 From: Greg KH To: David VomLehn Cc: Alan Cox , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Subject: Re: [PATCH] Combine two one-character CR-LF writes into one two-character write for O_ONLCR Message-ID: <20090813212750.GB24127@kroah.com> References: <20090813175430.GA8769@cuplxvomd02.corp.sa.net> <20090813205018.4d781c74@lxorguk.ukuu.org.uk> <20090813195554.GA22751@cuplxvomd02.corp.sa.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090813195554.GA22751@cuplxvomd02.corp.sa.net> 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 Thu, Aug 13, 2009 at 12:55:54PM -0700, David VomLehn wrote: > On Thu, Aug 13, 2009 at 08:50:18PM +0100, Alan Cox wrote: > > > do_output_char() function uses the struct tty_operations function write_room() > > > to determine whether it is possible to write two characters. It uses > > > tty_put_char() for each character which, for the USB generic serial driver, > > > translates into a write() for each character. For the USB generic serial > > > driver the value returned by write_room() only applies to the next write(). > > > > The USB serial driver is broken, fix it instead. It's not even hard to > > fix. > > > > > + tty->ops->write(tty, crlf, ARRAY_SIZE(crlf)); > > > + return ARRAY_SIZE(crlf); > > > > Emphatic NAK. Someone needs to actually fix the broken USB drivers for > > once. This is just one example of where the device will go kersplat if its > > broken, others include things like losing flow control. > > Works for me; please consider the patch withdrawn. I'll take a crack at fixing > the generic serial driver the right way; if other drivers are doing mix-and-match > with per-device code and generic code, they could get broken. I have no way to > test for this, so I'm hoping others will help out. I have a whole box of different usb-serial devices, and can test just about everything out. thanks, greg k-h