Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261967AbUCWEcs (ORCPT ); Mon, 22 Mar 2004 23:32:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261988AbUCWEcs (ORCPT ); Mon, 22 Mar 2004 23:32:48 -0500 Received: from smtp808.mail.sc5.yahoo.com ([66.163.168.187]:33671 "HELO smtp808.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S261967AbUCWEcq (ORCPT ); Mon, 22 Mar 2004 23:32:46 -0500 From: Dmitry Torokhov To: linux-kernel@vger.kernel.org Subject: Re: Synaptics touchpad + external mouse with Linux 2.6? Date: Mon, 22 Mar 2004 23:32:29 -0500 User-Agent: KMail/1.6.1 Cc: Joshua Kwan References: <20040322061657.GA346@ucw.cz> In-Reply-To: MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: <200403222332.31308.dtor_core@ameritech.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1981 Lines: 48 On Monday 22 March 2004 09:41 pm, Joshua Kwan wrote: > On Mon, 22 Mar 2004 07:16:57 +0100, Vojtech Pavlik wrote: > > I'm sorry to say it, but it's not possible. Well, it might be, but still > > the magic to recognize which device is sending the data would be rather > > crazy. > > Forgive me if I'm being naive, but... > > Why can't synaptics be transparent? Why can't it do all the stuff it > requires special userspace things for in kernel space? > > I should think that mapping the scroll buttons to their normal PS/2 > equivalents on a Synaptics touchpad is possible in kernel space. > > A friend recently expressed his discontent with this condition when he > tried to plug in another mouse and use it while the Synaptics touchpad was > still present. > > So, please enlighten me... > Because it is not implementation, it is hardware limitation. Synaptics native protocol uses 6 bytes, standard PS/2 3 or 4. The protocols are not compatible at all so unless the PC has an active multiplexing controller (which provides up to 4 completely independent AUX ports) all devices have to speak the same protocol. I have seen 2 different behaviors for PCs without active multiplexor: 1. Plugging external mouse forces synaptics into hardware PS/2 compatibility mode (Dells). 2. Hardware completely hides presence of external mouse (older Compaqs, ASUS). In this case psmouse.proto option is needed to force both devices use the same protocol, but all advanced features of Synaptics are lost. As a side note what is normal PS/2 equivalent lower left corner tap has? What about lower right corner tap? 3-finger tap? Synaptics provides much more features than you can have with standard PS/2. Hope that helps. -- Dmitry - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/