Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270510AbTG1PbU (ORCPT ); Mon, 28 Jul 2003 11:31:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270648AbTG1PbT (ORCPT ); Mon, 28 Jul 2003 11:31:19 -0400 Received: from delta.ds2.pg.gda.pl ([213.192.72.1]:7823 "EHLO delta.ds2.pg.gda.pl") by vger.kernel.org with ESMTP id S270510AbTG1PaE (ORCPT ); Mon, 28 Jul 2003 11:30:04 -0400 Date: Mon, 28 Jul 2003 17:43:51 +0200 (MET DST) From: "Maciej W. Rozycki" To: Andries Brouwer cc: Alan Cox , Pete Zaitcev , Chris Heath , Linux Kernel Mailing List Subject: Re: i8042 problem In-Reply-To: <20030728145452.GA1753@win.tue.nl> Message-ID: Organization: Technical University of Gdansk MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1095 Lines: 24 On Mon, 28 Jul 2003, Andries Brouwer wrote: > > Well, are timeouts needed at all? > > Yes. We send a command to the keyboard. It may react, or it may not. But we need not wait for that actively. If we are unsure about a result of a command, then we may send a command in question followed with an echo request. This assures an IRQ will finally arrive and if no command response arrives before an echo response, then the keyboard ignored the command. I used this approach many years ago to differ between PS/2 keyboards (which respond with 0xfa,0xab,0x83 to a request for ID) and genuine PC/AT ones (which respond with lone 0xfa). It worked. -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available + - 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/