From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270066AbTG1PgG (ORCPT ); Mon, 28 Jul 2003 11:36:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270069AbTG1PgG (ORCPT ); Mon, 28 Jul 2003 11:36:06 -0400 Received: from mailhost.tue.nl ([131.155.2.7]:10244 "EHLO mailhost.tue.nl") by vger.kernel.org with ESMTP id S270066AbTG1PgE (ORCPT ); Mon, 28 Jul 2003 11:36:04 -0400 Date: Mon, 28 Jul 2003 17:51:18 +0200 From: Andries Brouwer To: "Maciej W. Rozycki" Cc: Alan Cox , Pete Zaitcev , Chris Heath , Linux Kernel Mailing List Subject: Re: i8042 problem Message-ID: <20030728155118.GA1761@win.tue.nl> References: <20030728145452.GA1753@win.tue.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.25i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 28, 2003 at 05:43:51PM +0200, Maciej W. Rozycki wrote: > 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. And what did you do for XT? :-)