From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753450AbZHKQhk (ORCPT ); Tue, 11 Aug 2009 12:37:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752349AbZHKQhj (ORCPT ); Tue, 11 Aug 2009 12:37:39 -0400 Received: from exprod5og111.obsmtp.com ([64.18.0.22]:56079 "EHLO exprod5og111.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752067AbZHKQhj (ORCPT ); Tue, 11 Aug 2009 12:37:39 -0400 Message-ID: <4A819E80.90103@gefanuc.com> Date: Tue, 11 Aug 2009 17:38:24 +0100 From: Martyn Welch User-Agent: Thunderbird 2.0.0.22 (X11/20090608) MIME-Version: 1.0 To: "Emilio G. Cota" CC: Greg K-H , linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, Sebastien Dugue Subject: Re: [patch 1/5] Staging: VME Framework for the Linux Kernel References: <20090808230145.GB27151@braap.org> <4A801644.2070009@gefanuc.com> <20090810141442.GA18456@braap.org> <4A804283.5090009@gefanuc.com> <20090810193849.GA3055@braap.org> <4A812BCE.3010003@gefanuc.com> <20090811144914.GB32658@braap.org> <4A8189D9.4080709@gefanuc.com> <20090811153633.GC32658@braap.org> <4A819130.5080802@gefanuc.com> <20090811154226.GD32658@braap.org> In-Reply-To: <20090811154226.GD32658@braap.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Emilio G. Cota wrote: > Martyn Welch wrote: > >>> It wouldn't break it, the model simply couldn't give you more >>> than 8 windows-->8 devices. >>> >>> >> Unless the devices we the same and the driver reused one window. >> > > No, we agreed on that devices should know *nothing* about windows. > > Don't think I did. :-) I agreed that it would be impossible to assign sole use of 8 resources to 17 different drivers. I feel that there could be room and indeed a need for both approaches. It may be more efficient for a driver to use and move 1 window to position it's self over the registers of each of a number of compatible devices as required. Such a driver could exist side-by-side with drivers using your approach, that utilize a layer which removes such control. Whilst I understand you can assign a fairly sizable chunk of memory mapped IO for VME, this is not always the case. In situations where the available memory mapped IO is limited, placing a large window to cover 2 smaller windows with dead space in between them will not be an adequate solution either. Martyn > E. > -- Martyn Welch MEng MPhil MIET (Principal Software Engineer) T:+44(0)1327322748 GE Fanuc Intelligent Platforms Ltd, |Registered in England and Wales Tove Valley Business Park, Towcester, |(3828642) at 100 Barbirolli Square, Northants, NN12 6PF, UK T:+44(0)1327359444 |Manchester,M2 3AB VAT:GB 927559189