From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932181AbWFIIjV (ORCPT ); Fri, 9 Jun 2006 04:39:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751452AbWFIIjV (ORCPT ); Fri, 9 Jun 2006 04:39:21 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:36050 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S1751447AbWFIIjU (ORCPT ); Fri, 9 Jun 2006 04:39:20 -0400 Date: Fri, 9 Jun 2006 10:38:33 +0200 From: Pavel Machek To: Dave Jones , Sanjoy Mahajan , "Rafael J. Wysocki" , Paul Dickson , linux-kernel@vger.kernel.org, jeremy@goop.org Subject: Re: Bisects that are neither good nor bad Message-ID: <20060609083833.GD18084@elf.ucw.cz> References: <20060528140238.2c25a805.dickson@permanentmail.com> <20060528140854.34ddec2a.paul@permanentmail.com> <200605282324.13431.rjw@sisk.pl> <200605282324.13431.rjw@sisk.pl> <20060528213414.GC5741@redhat.com> <20060529145255.GB32274@redhat.com> <20060530152926.GA4103@ucw.cz> <20060603091133.GA24271@flint.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060603091133.GA24271@flint.arm.linux.org.uk> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.11+cvs20060126 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > With the resume failure I'm seeing, we don't get back to userspace > > > to run anything like this. It goes bang long before that. > > > > > > The SATA fix Mark proposed also didn't improve the situation for me :-/ > > > > If setserial -a is needed.. it means that someone really needs to fix > > suspend/resume support for serial... do it on working machine to > > enable debugging of broken ones... > > I've explained why this occurs in bugzilla - but for the sake of > repeating repeating repeating myself at great length, let's repeat > it again here. > > The serial layer does _not_ have access to the "current" termios > settings due to the layering by the tty subsystem. If the serial > port being used by serial console has been opened once by the user, > but is closed at the moment when a suspend/resume cycle occurs, > the serial layer and lower level drivers do not have access to the > baud rate. Could serial layer just cache "last baud rate" in some kind of software shadow register? Yes, it is slightly ugly, but should do the trick. > Hence, it is impossible for the serial layer to do a proper resume > in this scenario. Either always suspend with the console port open > or never open the console port before suspend. Alternatively, we > need the tty layer to mature, so that there is some way for drivers > to get the termios structures for the console from the upper layer. > Or maybe we need the tty layer to be responsible for implementing > suspend/resume support for tty devices. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html