From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932179AbWFBWlt (ORCPT ); Fri, 2 Jun 2006 18:41:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932581AbWFBWlt (ORCPT ); Fri, 2 Jun 2006 18:41:49 -0400 Received: from mx1.redhat.com ([66.187.233.31]:62387 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S932179AbWFBWlt (ORCPT ); Fri, 2 Jun 2006 18:41:49 -0400 Date: Fri, 2 Jun 2006 15:41:21 -0700 From: Pete Zaitcev To: Greg KH Cc: lcapitulino@mandriva.com.br, linux-kernel@vger.kernel.org, rmk@arm.linux.org.uk, linux-usb-devel@lists.sourceforge.net, zaitcev@redhat.com Subject: Re: [PATCH 8/11] usbserial: pl2303: Ports tty functions. Message-Id: <20060602154121.d3f19cbe.zaitcev@redhat.com> In-Reply-To: <20060602205014.GB31251@suse.de> References: <1149217397133-git-send-email-lcapitulino@mandriva.com.br> <1149217398434-git-send-email-lcapitulino@mandriva.com.br> <20060602205014.GB31251@suse.de> Organization: Red Hat, Inc. X-Mailer: Sylpheed version 2.2.3 (GTK+ 2.8.17; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2 Jun 2006 13:50:14 -0700, Greg KH wrote: > On Fri, Jun 02, 2006 at 12:03:14AM -0300, Luiz Fernando N.Capitulino wrote: > > 2. The new pl2303's set_termios() can (still) sleep. Serial Core's > > documentation says that that method must not sleep, but I couldn't find > > where in the Serial Core code it's called in atomic context. So, is this > > still true? Isn't the Serial Core's documentation out of date? > > If this is true then we should just stop the port right now, as the USB > devices can not handle this. They need to be able to sleep to > accomplish this functionality. > > Russell, is this a requirement of the serial layer? Why? Shouldn't it be all right to schedule the change at the moment of that call and have it happen later? Resisting a temptation to abuse keventd and schedule_work and using a tasklet may help with latency enough to make this tolerable. I'm sure that a generic mechanism to drive asynchronous usb_control_msg is going to be required as well for this project. The pl2303 is just lucky to avoid it. -- Pete